An Investigation of the Photochemical and Spectroscopic Properties of Chromium, Molybdenum, Tungsten, and Rhodium Isocyanide Complexes Citation Mann, Kent Robert (1977) An Investigation of the Photochemical and Spectroscopic Properties of Chromium, Molybdenum, Tungsten, and Rhodium Isocyanide Complexes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/s9tb-gr40. https://resolver.caltech.edu/CaltechTHESIS:08132024-203836380 Abstract The X-ray crystal structure of Cr(CNPh) 6 has been determined. The complex crystallizes in the space group R3 with one molecule in the unit cell a = b = c = 10.628Å; α = β = γ = 111.17°; V = 861.1 Å 3 . The metal atom has crystallographic site symmetry S 6 with the MC 6 framework forming a perfect octahedron. The Cr-C-N bond angles are all 174.7°, the Cr-C bond lengths are 1.933(2)Å, and the C-N bond length are 1.168(2)Å. Both infrared spectra, X-ray crystal structure data, and electronic absorption spectra are consistent with the operation of a second order Jahn Teller distortion of the ground state of Cr(CNPh) 6 . Data obtained on the sterically hindered systems Cr(CNDph) 6 and Cr(CNIph) 6 [Dph = 2,6-dimethylphenyl and Iph = 2,6-diisopropylphenyl] also support the operation of a Jahn Teller effect. Similar considerations apply to the Mo and W systems. The electronic absorption spectra of M(CNAr) 6 [M = Cr(0), Mo(0), W(0), Ar = phenyl, ph; 2,6-dimethylphenyl, Dph; and 2, 6-diisopropylphenyl, Iph], Mn(CNP'n) 6 Cl and [Mn(CNPh) 6 ](PF 6 ) 2 are reported. Each of the M(CNAr) 6 complexes exhibits intense allowed metal-to-ligand charge transfer (MLCT) absorption bands between 20.8 and 32.7 kK. The lowest MLCT bands are observed at 29.9 and 31.1 kl( in the electronic spectrum of Mn(CNPh) 6 + . Low energy bands at 18.2 and 20.4 kK in [Mn(CNPh) 6 ] 2+ are assigned to vibronic components of a σ(CNPh) → dπ charge transfer transition. The unique electronic structural properties of arylisocyanide complexes are apparently related to the π conjugation of aromatic ring orbitals with the out-of-plane π*(CN) function. The emission and photochemical behavior of M(CNPh) 6 and M(CNIph) 6 complexes (M = Cr, Mo, W; Ph = phenyl, Iph = 2,6- diisopropylphenyl) has been studied. The complexes of Mo and W show emission attributable to an Lπ* → dπ process in a variety of solvents (2-methylpentane, 2-MeTHF, benzene, pyridine) at room temperature. Complexes of all three metals show emissions at 77 K in 2-MeTHF that overlap the MLCT absorption bands. The emission quantum yields for Mo(CNIph) 6 and W(CNIph) 6 in 2-MeTHF at 77 K are 0.78 ± 0.08 and 0.93 ± O.07, respectively. The emission lifetimes at 77 K ir: 2-methylpentane for the M(CNIph) 6 complexes are: τ(Cr) less than 10 nsec, τ(Mo) 40.2 ± 0.5 μsec (298 K, 43 ± 2 nsec), τ(W) 7.6 ± 0.5 μ sec (298 K, 83 ± 2 nsec). Both M(CNPh) 6 and M(CNIph) 6 undergo photosubstitution reactions in pyridine solutions. Formation of M(CNPh) 5 py and M(CNIph) 5 py occurs upon irradiation at 436 nm, with quantum yields decreasing according to a regular pattern [Cr(CNPh) 6 ] (0.23) ~ [Cr(CNIph) 6 ] (0.23) > [Mo(CNPh) 6 ] (0.055) > [Mo(CNIph) 6 ] (0.022) > [W(CNPh) 6 ] (0.011) >> [W(CNIph) 6 ] (0.0003). The very small quantum yield for photosubstitution in the case of W(CNIph) 6 is interpreted as an indication that the mechanism of formation of W(CNPh) 5 has associative character. Irradiation of M(CNIph) 6 at 436 nm in CHCl 3 yields the one-electron oxidation products [M(CNIph) 6 ]Cl. The quantum yield in each case is 0.19 ± 0.01. Similar irradiation of M(CNPh) 6 in CHCl 6 gives two-electron oxidation products. For M = Mo, W, the products are identified as the seven-coordinate species [M(CNPh) 6 Cl] Cl. The room temperature UV-VIS solution spectra of Rh(CNR) 4 + [R = aromatic or aliphatic] have been found not to follow Beer's law. This behavior has been attributed to complex oligomerization of the monomeric Rh(CNR) 4 + units to form species of the type [Rh(CNR) 4 + ] n (n = 1, 2, 3). The extinction coefficients and formation constants using the following expressions: M + M K 1 ⇄ D D + M K 2 ⇄ T have been obtained for the systems R = phenyl in acetonitrile solution; and R = t-butyl in water solution. The values for the parameters used are for R = phenyl, K 1 = 35 M -1 , ε 2 = 10,500, ε 2 K 2 = 183,000 M -1 ; for R = t-butyl, K 1 = 251 M -1 , ε 2 = 16,900. The nature of the oligomerization is due to a direct metals metal interaction of the d 8 Rh atoms. The band positions for the oligomeric species were found to conform to predictions made by simple Hückel theory. The synthesis and characterization of a dimeric Rh(I) complex containing the bridging ligand 1,3-diisocyanopropane(bridge) is reported. In methanol solution, [Rh 2 (bridge) 4 ] 2+ oligomerizes, and species containing four, six, and eight Rh atoms have been identified spectroscopically. The dimer, [Rh 2 (bridge) 4 ] 2+ , undergoes two center oxidative addition reactions with I 2 , Br 2 , and CH 3 I. The products, [Rh 2 (bridge) 4 X 2 ] 2+ (X = I, Br) which contain two strongly coupled Rh(II) atoms, possess trans stereochemistry. The mechanism of oxidative addition is thought to involve attack of the Rh(I) on the heavy atom of substrate molecule. Item Type: Thesis (Dissertation (Ph.D.)) Subject Keywords: (Chemistry) Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemistry Thesis Availability: Public (worldwide access) Research Advisor(s): Gray, Harry B. Thesis Committee: Unknown, Unknown Defense Date: 8 September 1976 Record Number: CaltechTHESIS:08132024-203836380 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:08132024-203836380 DOI: 10.7907/s9tb-gr40 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 16632 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 13 Aug 2024 23:01 Last Modified: 30 Oct 2024 01:13 Thesis Files PDF - Final Version See Usage Policy. 53MB Repository Staff Only: item control page

An Investigation of the Photochemica l and Spectroscopic Properties of Chromium, Molybdenum, Tungsten, and Rhodium Isocyanide Complexes Thesis by Kent Robert Mann In Partial J?ulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 1977 (Submitted September 8, 1976) ii Copyright@ by Kent Robert Mann 1976 iii ACKNOWLEDGMENT I wish to acknowledge the help and tolerance of Chris, Harry, George, Nate, Greg, Mike, Bruce, Dave, Bi.11, ClaudeJ and, aw hell, everybody. I especially acknmvledge the~ incredible amount of ,vork done by Nate Lewis from whom we may all be ta.king orders someday. Harry, I'll get right on it. iv ABSTRACT The X-ray crystal structure of Cr(CNPh) 6 has been determined. The complex crystallizes in the space group R3 with one molecule in 0 0 3 the unit cell a =b = c = 10. 628A; a =/3 = y = 111.17°; V = 861..1 A. The metal atom has crystallographic site symmetry S6 with the MC 6 frarn.ework forming a perfect octahedron. The Cr-C-N bond angles are all 174.7°, the Cr - Cbond lengths are l.933(2).A, and the C-N bond length~ are 1.168(2).A. Both infrared spectra, X-ray crystal structure data, and electronic absorption spectra are consistent with the operation of a second order Jahn Teller distortion of the ground state of Cr(CNPh) 6 • Data obtained on the sterically hindered systems Cr(CNDph) 6 and Cr(CNiph) 6 [Dph = 2, 6-dimethylphenyl and Iph = 2, 6-diisopropylphenyl] also support the operation of a Jahn Teller effect. Similar considera~ tions apply to the Mo and \V systems. The electronic absorption spectra of M(CNAr) 6 [M = Cr(O), Mo(O), W(O), Ar= phenyl, ph; 2,6-dimethylphenyl, Dph; and 2, 6-•diisopropylphenyl, Iph], Mn(CNP'n) 6 Cl and [ Mn(CNPh) 6 ] (PF 6 \ are reported. Each of the M(CNAr) 6 comple,xes exhibits intense allowed metal-to-ligand charge transfer (MLCT) absorption bands between 20. 8 and 32. 7 kK. The lowest MLCT bands are observed at 29. 9 and 31. 1 kl( in the electronic spectrum of Mn(CNPh\ +. energy bands at 18. 2 and 2 0. 4 kK in [Mn(CNPh) 6 ] 2+ Low are assigned to vibronic components of a a (CNPh) ..... d1r charge transfer transition. V The unique electronic structu ral properties of arylisocyanide complexes are apparently related to the rr conjugation of aromatic ring orbitals w ith the out-of-plane 1r *(CN) function. The emission and photochemical behavior of M(CNPh\ and M(CNiph\ complexes (I\/(== Cr, Mo, W; Ph = phenyl, Iph = 2,6diisopropylphenyl) has been studied. The complexes of Mo and W show emission attributable to an Lrr * - drr process in a variety of solvents (2-methylpentane, 2-M:eTHF, benzene, pyridine) at room temperature. Complexes of all three metals show emissions at 77 K in 2-MeTHF that overlap the l\1LCT absorption bands. The emission quantum yields for Mo(CNiph\ and W(CNiph) 6 in 2-MeTHF at 77 K are 0. 78 ± 0. 08 and 0. 93 ± O. 07, respectively. The emission iifetimes at 77 K ir: 2-methylpentane for the M(CNiph) 6 complexes are: T(Cr) < 10 nsec, T(Mo) 40.2 ± 0.5 µsec (298 K, 43 ± 2 nsec), T(y/) 7. 6 ± 0. 5 µ sec (298 K, 83 ± 2 nsec). Both M(CNPh\ and M(CNiph) 6 undergo photosubstitution reactions in pyridine solutions. Formation of M(CNPh) 5 py and M(CNiph) 5 py occurs upon irradiation at 436 nrri, with quantum yields decreasing according to a regular pattern [Cr(CNPh\] (0. 23) ~ [ Cr(CNiph) 6] (0. 23) > [J\1o(CNPh) 6] (0. 055) > [Mo(CI\TJ:ph) 6 ] (0. 022) > [W(CNPh) 6 ] (0. 011) >> [W(CNiph) 6 ] (0. 0003). The very small quantum yield for photosubstitution in the case of W(CNiph) 6 is interpreted as an indication that the mechanism off ormation of W (CNPh\py has associative character. Irradiation of M(CNiph) 6 at 436 nm in CHC1 3 yields the one-electron oxidation products [M(CNiph\]Cl. The quantum yield vi in each case is 0. 19 :i: 0. 01. Similar irradiation of M(CNPb \ in CHC1 3 gives two- electron oxidation products. For M = Mo, \V, the products are id entifi ed as the seven - coordinate species ~.1(CNPh) 6 Cl] Cl. The room temperature UV - VIS solution spectra of Rh(CNR) 1 + [R = aromatic or aliphatic] have been found not to follow Beer's law. This behavior has been attributed to comple.."'IC oligomerization of the monomeric Rh (CNR) 4 + units to form species of the type [Rh (Cl'JR) 4 +] (n = 1, 2, 3). 11 The extinction coefficients and formation constants using the following expressions: D M+M D + M ~ T Kz have been obtained for the systems R = phenyl in acetonitrile solution; and R = t-butyl in water solution. are for R = phenyl, K1 = 35 M -1 The values for the parameters used , 6i = 10,500, E3 K2 = 183,000 M -1 ; for R =t-butyl , K1 == 251 M- 1 , ½ =16,900. The nature of the oligomerization is due to a direct metals metal interaction of the d Rh atoms. The band positions for the oligomeric species were found to conform to predictions made by simple Ruckel theory. The synthesis and characterization of a dimeric Rh(I) comple..""\: containing the bridging l~gand 1, 3-diisocyanopropane(bridge) is reported. In methanol solutiori, [Rh 2 (bridge) 1 ] 2+ oligomerizes, and species containing fo ur, six, and eight Rh atoms have been vii identified spectroscopically. The dimer, [Rh2 (bridgc) 4 ] 2+ , undergoes two center oxidative addition reactions with½, Br 2 , and CH 3 I. The products, [Rh2 (bridge\Xzl 2+ (X = I, Br) which contain two strongly coupled Rh(II) atoms, possess trans stereochemistry. The mechanism of oxidative addition is thought to involve attack of the Rh(I) on the heavy atom of substrate molecule. viii TABLE OF CONTENTS TITLE CHAPTER 1 PAGE Preparation, St ructural Characterization 1 and Excited State Properties of Hexacoordinate Aryl Isocyanide Compl exes of Cr(O), Mo(O), and W(O) 2 169 Spectral Characterization of Rh(I) Isocyanide Complexes 3 The Preparation, Spectral Properties and 197 Oxidative Addition Reactions of a. Dimeric Rh(l) Isocyanide Complex Rh 2 (br idge)4 Propositions 2+ 209 1 CHAPTER I PREPARATION, STRUCTURAL CHARACTERIZATION, AND EXCITED STATE PROPERTIES OF HEXACOORDINATE ARYL ISOCYANIDE COMPLEXES OF Cr(0), Mo(0), AND W(0) 2 Introduc tion Surprisingly little is known about the electronic structllre and photo chem istry of isocy,inicle complexes, in spite of the strong current interest in the coordination chem is try of isocyanides and the obvious relationship of these ligands to cyanide ion and carbon 1 2 • tl1eore t·1ca1 wor k on 1socyan1L • •de cornp1exes , monox1•d e. •• 1 p rev10us appears to be limited to a few semi-empirical molecular orbital 4 3 calculations, ~ incomplete electronic spectral data, 4 , 7 - 11 and one photochemical study. 13 The approach used in attacking this area was to obtah1 an overview of the complexes' electronic structure and to explore the photochemical reactions which were suggested by the nature of the excited states. Low valent complexes containing only isocyanide ligands of Cr(0), Mo(0), W(0), and Mn(l) and (II) have been kno,x.rn for quite 1 some time. • They are usually synthesized from simple metal 14 15 6 complexes (Cr 2 (C 2 H 3 O2 4· 2H 2 O, Mo 2 (C 2 H 3O2 ) 4 , wc1/ , and 17 Mnl 2 ) by addition of the appropriate isocyanide and in some cases a reducing agent such as magnesium. In Malatesta 's and Bona ti's 1 book and in several more recent reviews,. the chemistry of iso3 4 cyanide complexes of metals is reviewed. l, ' The M(CNAr) 6 compJ.exes (where M = Cr(0), Mo(0), W(0)) are obtained as very thermally stable dark red to orange crystals that are stable to ai:r in the solid state indefinitely (for M = Cr(0)) or for a few days (M = Mo(0) andW(0)). The Mn(I) complexes are air stable, being much n10re stable than the corresponding Mn(II) complexes 3 which under proper conditions are sponta11eous 1y reduced bac.k to the 1 Mn(I) complexes. G Having low-spin d configurations, one expects that ther:::nal ligand exchange :reactions would be rather slov;. This is born o out 3 14 by experiment, the half life for exchange of Ci la.be led phenyl isocyan ide with Cr(CNPh) 6 being about 250 hours at 20 °C. This 13 rate is slower than the rate for the exchange of C O with Cr(CO) 6 • 15 Early in our work on the elect1~onic structure of Iv'l(C:NPh) 6 complexes (whe re M = Cr(0), Mo(0), VV(0)) it became obvious that an X-ray crystal structure would be needed to clarify the structura l ambiguities suggested by the electronic spectra and the ii(CN) . o f• l11e m1rare ~ d spec t ra. 11 ' 12 ' 18 reg10n ,LJ.. • 4 X-ray Crystal Structure of Cr(CNPh) 6 11._~~ Red crystals of Cr(CNPh) 6 were obtained by slow cooling of a saturated toluene soluti.on of the complex. The crystals were found to be rhombohedral in shape and of X-ray quality. A crystal, 0. 24 mm on an edge, was selected and mounted so the spindle axis was perpendicular to the apparent three-fold symmetry axis of the crystal. Weissenberg photographs initially suggested that the space group was triclin ic but a precession photograph showed the threefold symmetry present in a heY.agonal/rhombohedral unit cell. By fitting fifteen observed reflections with the program CELL 19 and examining the data set for absences, the space group was determir1ed to be [R-r; 148] . Data were collected on a Datex automated General Electric quarter circle diffractometer and the unit cell dimensions were 19 determined by a least squares procedure program using 28 values measured for sixteen reflections. More information is given in Table· 1. Determination and Refinement of the Structure Symmetry considerations require that the metal sit. on the inversion center of the unit cell. This requires that all six ligands be equivalent. Thus only the positions of nine nonhydrogen atoms needed to be found. The program MULTAN 20 was used to solve the structure using 100 strong reflections. Least squares 21 refinement of the structure anisotropically for all nine nonhydrogen atoms and isotropically for the five 5 Table 1. E xper imental Data for the X--ray Diffrac tion Study of Cr(CNPh) 6 - Space group [R3; No. 148] Rhombohedral Cell Hexagonal Cell a =b = c, A 10.628 a = b = 17, 535 A c = 9. 701 A a= f3 = 90 ° a=(3 =y 111.17° 'Y = 120 ° 0 3 V, A V = 2283. 3 861.1 z = 1 z =3 Mol. wt. 670. 74 p calcd g cm- 3 1.294 p obsd (floatation in CC14 / pentane) 1. 3. Radiation graphite-monochromatized MoKa (11. c 0. 71069 A) Scan mode coupled e - 2 e . Scan speed 1 ° /min. Range 1. 5 ° < 20 < 40 °. Background 20 sec at beginning and end of each scan. Reflections collected: 2354 including equivalent forms to give 750 unique data reflections. Absorption coeff: µ = 3 . go cm -1 . 6 hydrogen atoms yield R 1 and~ of 0.0311 and 0.0311 for R 1 = I; 11 F I- IF c II / ~ IF I and O O R2 2 2 I I- IF c lj 6w IF I ½. = ( 1~ w ( F O \' The GOFparameter, GOF = [ 1._Jw(F 0 2 / 22 O ) _!_ Fe) /(m- s)] 2 is 1.5215. A three dimensional difference Fourier synthesis 19 calculated at - the conclusion of the refinement indicated no discrepancies greater than ± 0 . 21 A". Discussion The metal atom sits on a site of S 6 symmetry, allowing a distortion along the three fold crystalographic axis such that the four··fold axis present in an octahedron vanishes. The distortion takes the form of a deviation from linearity of both the M-C-N angle and the Ci80 -N-Cring angle of about '7°. The two planes defined by these two sets of _three atoms however do not coincide, the dihedral. angle between the plane normals being 59.15°. The M-C. 180 -N plane normal also makes an angle of 89. 2 ° with the three fold symmetry axis. This can be visualized easily by taking the M(CN) 6 frame wo1·k and bending all of the MCN bond angles toward the plane perpendicular to the three fold axis of the complex, reducing the symmetry of the M(CN) 6 portion of the molecule from Oh to D3d. Addition of the phenyl rings further reduces the symmetry of the molecule to that of the site symmetry, which is S6 • The phenyl rings are arranged in an almost perfect Th fashion about the Cr atom . . Each ring normal . is tipped 6. 86 ° away from one of the two fold axes of a Th structure while it is nearly perpendicular (88. 97°) to the other unique two-fold. (The angle made with the third two-fold is 90 ° + 6. 86 ° = 96. 86 °.) 7 This reductio11 in the syrnmetry cf the molecule from Th to s was predicted from the ~ (CN) stretching region of the infrared 15 spectrum. Infrared data will be discussed in relation to G structural eons iderations in a following section. T,he bond leng,ths and angles are set out in .Tables 2 a,nd 3. The metal-carbon bond length of 1. 933(2).A is close to that found in 0 Cr(CO) 6 where the M-C bond length is 1. 92 ± 0. 04A. 25 The carbon-nitrogen triple bond is 1. 168(2).A which compares favorably to those found in other phenyl isocyanide structures. 26 The six carbon atoms of the phenyl rings form nearly perfect hexagons; the C-C bond lengths b2ing (1. 374 ± 0. 018 A.); deviations from coplanarity being less than 0. 007 A. ~ Symmetry considerations suggest that a M(CN) 6 fragment having perfect Oh symmetry should give rise to one infrared active T 1u v(CN) stretching mode. If, however, one reduces the symmetry to D3 d by applying a trigonal distortion to the M(CN) 6 fragment, the triply degenerate T 1u v(CN) mode is split into a singly degenerate Azu and doubly degenerate Eu mode. Further lowering of the symmetry from D3 ct to S6 only changes the appropriate symmetry labels, maintaining the degeneracy of the Eu mode. (The new labels in S6 are Au and Eu.) Reduction of the M(CN) 6 fragment from Oh to Th does not split the degeneracy of the triply degenerate Tiu v(CN) mode (Tu in T 11). Interesting.ly, infrared spectra of 8 Table 2. Bond Distancesa for Cr(CNPh) 6 CR - C( ! ) lo·n3( 2J Cl2l - C(3) - lo3.J3{ 2) C{2) - C{7l C ! 3) - C ( 1.t} lo376{ 2} C(3l - H(3) C(4J - HU:- ) CC6} - H{7) C{5l - . C{6l CoSSl(ltl lo3Cif:( 2) CC6) - CC7} ((7) - 1-'{7) Oo8~2<lcl CC5l - rC5l OoS79(1S) - 1-(6) Ov925(22l loS83{16) . --· -©! 0 '- l a . . 2/ Numbering system ,s CccN . _6 3 4 C C6 } 5 9 Table 3. Bond Anglesa for Cr(CNPh) 6 -C(ll-N N - C(2) - ([71 C( 2 ) - C!ll - h(3J __ C! 2 1 - 17 1,073( 15) _____ C(l _l _- _ !\ ___ ___ _- C 12 ) __ 173,3 0 ( 17! CI :3 I - C ( 2 l :-. C I ·1 l C_!71 _ - __H7l___ __ 1_17,,S_'dll41_ C( 3 l - Cl 2 l -:-ffC-7 l • C(3J - C( ; J - C( 5 1 ___ C ( 4 l .. - . _C ( :, i _ - __C_(_6l _____ l 1So97 ( __ 18 )__ C(51 - (( :,. ) - t-( 4 1 •• Clo) .:.. CC71 - Hll 11So60 (l O3 ) C I'• l - C ! 5 l - f-iT5 l __.. C_( 5 I - C( 6 l - 11So 3t (112l C ( 7 l _ __ ~ 2 '.lo 7 s ( 1 9 I C(_?). __-:-_ C.(~l __ :-__H_l 6 ) • ! 1904 8 114·'.:l 143.69( C(5l - C(2l - C(7l - C(6l -- - ----- - -· C! 3 l - H(6l l l9o 68 ( h ) l . - -- . . .. 11900 4 ( 17) - 75 _, 07( _6.J) C(41 - C(6l - b6l -- - - ---- - ···- -- -- ---···- - · · ·- -- -- ·· . ... H(6l - C(6l - H(7J 98o37(h 3 l H(3) a Number system is the same as for Table 2. 10 Figure 1. View of Cr(CNPh) 6 down the three-fold axis. 11 Figure 2. stereoscopic view of Cr(CNPh) 6 down the three-fold axis. 12 Table 4. Atomic Coordinates in Terms of the Rhonbohedral Cell Atom C~ J 0 0 z y X ( JJI OoO 20) CoC ( ?el ~J J J 1 1 7 GCJ { 3 u ) • 0 0 3 (; l J. 3 ( 2 8 ) C{'. l 3 (: 1t 2 \ 2. :3 ) C(l) J ..,,JC: 658 ( J ;J} Cc222 1 L1( :2i (.,Crc5C:( 2S ) C(2) ) ,,1773:J( 32) Oo:.2185{ .:-:)) ro1G 8 SS( 2 S) -· -C ( 3} - -·-· ) 0 Cl 7::, 6 { • 3 4) -· CO 5 7 6 6 .j ( - 2 2 r - -- ( ~ 1n ~q 2 c ---3-z-f : { -~ ) J .., l 3 2 6 g ( 36 ) 0 .'.) 7 :3 1+ 1 6 { .:: 2 ) Cc 2 ~ 2 5 7 ( 3 2 l C{5) Jo2845CI 40} 0083731( 37) Co277SS! lt) C( 6 i ) " 3 8 5 1t 1) ( 4 l ) C o 7 2 5 7 O ( !1 l ) r o 2 f-< ·10 <: ( 1-t t) ) C(ll ).,333 8 3( 371 Cof.27 b ::i{ 3~} ·co2V)7C( 3 6) H(J) - )0 0 7'7 .?>3{3.?l) Col;S.S52(3Cil CoHc5C(2S2l --- H ( /-t l • --- .Jo C GD ? 2 ( 3 5 9 ) • - C; 7 7 G 7 9 { 2' 3 5 ;- - -- c~ 2 2 8 3 S "( 3 2 t1 -H( 5 } J., 3 2 C: 7 C ( 3 5 6 ) 0 o S 11 8 1 , .3 ( 3 :l 8 ) ( o ? t) 7 2 l ( 3 ~ 4 ) 1 H!6) H( 7 } Jo49175(4~1) ,J O ?., s 5 1: 3 ( 3 2. 9 ) CoE5893(420) C 5s 3 59 ( 3 2 1 ) O Ca31772(~0 9 1 CO 2 11 l 5 : ( 3 l 7 ) Table 5. Atomic Coordinates in Terms of the Hexagonal Cell Atom - X y z o.. o o.o o.. 0 COORC CR CR COORC N NI -O .. G87410 0 ... 068620 0.205100 COORD C ( 1) c• -0 .. 056027 0., 0Lt4 l07 O.. 1226C7 CCORC C C 2 ) CI -O .. lld647 0 .. 107.257 Oe2CJ5SLt7 CCORC C(3) C' -o. 203533 COCRD C(4) c• COCRC C ( 5) C I -o., 181997 0 .. 18B8l6 o. 't66496 CCCRC C ( 6) C' --0. 09cU 30 CCORD C ( 7) C' -0 .. C6S6.30 0.162760 0 • .399460 COGRD H(3) HS -0 .. 239893 O.. G56O6J 0..,'202563 COORD H ( t.t) HS -00292913 Oo 12L"7L-;J 0.353133 CCCRO H ( 5) HS -- 0 • 2 C:~, 7 ti 7 0 ... 2182J7 CCCRD H(6} HS -0.06 1-t-38..3 CCCRO H ( 7) HS -0 .. 0l-t7.60 0., 1686 ;'tO 0oLil0190 0,,092173 ()~ 2 SC 893 -0.233783 0 .. 133903 0 .. 366 1,73 0 o 2 036 lii) Oo4837JO 0 .. 5254 1t7 o .. z33 ,,13 0.556133 13 Table 6. Final Thermal Parameters for Cr(CNPh) 6 Atom /322 /311 - MO SDaCR {333 o. 002626-/ 0.0026267 C, ClC t1 033 0.0026267 /323 /313 /312 o.o o.o Md SC: N 0.00 62633 0.0061600 0.0150133 o. 000 '12 6 7 0.004 9933 0.0015533 /:.NISC C ( 1l O. C035Cll ().003 65 78 O. OlJldJ 4:t 0.0037 5 ll-J.000 0956 O.UOl5822 AN ISO C(2) o. 00 't5433 0.004::..267 0,0111133 0.0050600 0.0027D3 0,0021 1,0J AN'ISC C ( 3 i O.OC4 32S9 0. 0 Q/; J 13 9 C.0114369 0.C0-1 od22 o.oooao22-o.ooos022 f.NISO C(4) 0. 0046 l 1tll M!I SO C ( 5 l o.oo674J9 0.005:3222 o.o 133 7.39 1\1-!1S0 Ci-'>) 0. ,l 06 951 l M'\lSO C(7l o. 00532 1,t; o. 012 1, 'ti 1 O. 00'..>511 l o. 0030 (hL, 0.0JJ7J56 o. 006 SltiF) o.0034022-o.0009ua? 0.0Go56ll 0.012 8244 0.00 4~77d-0 .0 02535G-0.005 l64 4 0.0048778 0.:)070211 o. 01 1t3 5 7J 0.UJSlill-0.0007 356 0.0Ulfo69 - --~- --· B Atom b I SO H{3) 2.56 8 51 1SC H(41 3.764 !SG I-! ( 5) 4.4797 ISC Hio} 6. 39606 ISO H{7) 3. 15154 2 2 *2 aThe form of the anisotropic temperature factor is exp(-2,r (h a r *c * /3 23)]. ... + 2Klb bThe form of the isotropic temperature factor is of the form 2 2 exp[ -B(sin G/A )] . /311 + 14 Table '7 . Calculated and Observed Structure Factors }< I_ H K H FOt>S F OL\S L FCAL -J. 3 -13 -2 -3 -13 - It - l 1t -· 1 1t -lit -15 -15 -11 -1 J. -11 -11 -11 -11 -11 -12 -12 25o3J J.5.20 -1 -2 -!1 909 1t -3 -3 ·- 2 - 1 -2 -1 -2 -2 lft.2 l LL•'t0 l O I~ 6 Ut. 59 _, -~ -5 -6 -7 -1 -2 -3 -12 -12 -12 -l -5 -6 -1 -2 -13 -13 -11 -13 -5 - l l~ -14 -14 -1 -15 -10 -10 -10 -10 -10 -lC -10 -10 -11 -11 -1 1 -11 -'.l -2 -3 -1 -1 -:-2 -3 -4 -5 -c -7 -8 -1 - ?. - l 1t • 4 6 -6 35Q6/+ - l 7,. 7 2 c; l '..i n C ·1 25.98 l 1t . 26 8 • i 1t J.l., 76 36.84 17.59 -9 -l1 -9 -9 -5 8048 -11 ·-11 -11 -12 - l -· 2 -12 _, 1 2 -2 -1 -3 C --12 -t., l l -. L. 2 -s -· l 0 -· 7 1 -9 -9 -8 -- 1 2 3 _, 6 0 ,. I+ S 3.,06 4o0l 20. 26 8., 11 2.,75 24. 91 -11 -1 12.,ltZ 11 .. 51 -11 -11 0 L99 15 ~4 l 13., 61 9o08 1.49 2.60 43057 5 .. 7 5 L► 5 5 7 2. l 6 35 ,.td J 5 .,41 Q I. l:.J 3 , 5J 13 1t 0 3ti.,A 3 J. J. J J J'S .. 7?. 0 -11 CLJ7 6 .. 19 -11 -11 3.85 25~65 7 • Lt 3 -12 -12 -12 -12 -13 13.56 12., 91 9 <> 5 11 4 li O JolJ5 4 1+. 33 6., <,7 4-5 .. ::>8 2" (-: l 13.t;s 38~47 0 33.Sl 3 3 .. (, 11 9,20 6.67 1t a j 6 -2 ·-2 20 .. 15 -3 -1 16 ,,l~ 7 2 9 .. 5 '• 2 l. o 11 l l6u32 -I, C 23 .. 6 3 23 ,,93 - r. -f:. 1 2 17095 27 .. 02 25.92 9 l 7.61 3o 51 t~27 1t 1 -3 -4 -5 3 -6 '* 7. 6 '.3 22059 - 1 1 2 12"' 0 !J 39,, 8 1t 3 39,30 1t.. 7 l l6o08 7 .. 1t9 21.. 61 9 .. 69 9 .. 02 23 o l 7 l2o20 38 .. 39 :·H ~ 1t () 4- 2 {t 16 2:1 -~ 2 -3 0 8039 1 2L,L)5 11.11,, 2 1, -13 35~58 3 L 22 -8 -1 - Ii 74 l i 1 -8 -8 -8 -8 -2 -3 1t 11., 0 l.1 -2 L14 ~ ·t2 - Lt - 1 -5 -6 -7 -8 C 1 2 3 13., 11 35 . Jl 19, 8 7 2J~ 9 "J 17 ~ 6 ') 73. 6'3 2.. Jl) 1r 1-i o 23 1.~ ... 02 -(_) 4 2L4 1. -, --1 ... 2 -3 -· 2 .1 1t . fl 8 -8 -8 -e -8 -9 _Q 1 j - (; ,, 35 ~ us -9 3'..5.Sd 29 3 3 19.62 7., 28 -4 -1 -2 -9 -9 -9 -9 14. Cl 25070 65 .. 22 6.16 3.C3 10.56 0 133~25 46079 1t • 80 J. 9 ~ 9g -Z Z., 5<J l9,,S2 l. 00 18. 2 8 82otl9 3 3 31 25.94 15 .. 07 37.33 - 1 0 -3 -2 17065 26" 11 -1 -2 l -'• -3 - 1, -7 " 0 l -5 20 •4 1t 2 o "i 1t , -10 6097 -· 1 2l-t.,36 l Oo l 9 2 1t. 9 5 u -3 -2 2 Q" iJ It 0.70 3 .. 18 1 l.,,05 7o30 - t, 2 3 2 Oo7l l -1 _c; l 41. ti d 2.06 14~ 13 42.19 29,29 J. -6 4 1t ~ G 6 4lo28 10.53 0 7 .. 83 5•8 1t .l Lt.25 t9 o O Q -3 -2 -1 C 't3 313 -6 -s FCAL C -10 -10 -10 -10 -10 -10 1 - It 0 -1 -2 -3 22.53 1t c; o 1t S 13 .. 17 51.GS lt2 • 7 3 30.52 -3 -2 -11 -9 8 .. 0B -1 -13 - 1 '• -14 -9 -9 22~48 110 6 1 -1 -2 -3 1.4. 20 L,82 -3 -2 -1 -5 L,7.56 -13 -13 -13 .• 2 ·-1 14.(8 10 ¢ C7 -/1 -2 -5 4 -7 -3 -4 -5 -6 -7 -12 l r>. ::i 0 -4 -3 -12 -13 -13 _i:; _, "J '• - l C $ 0 ,0 {i Vt,, 5 l 19 0 'i). 20.99 llcOO 7-lol2 13. 51 10~1<1 8., l1 :> J0.29 2S.09 Jo., 5 3 ✓.: ') o J 2. -L1 t 2 d .i:.l7 -6 2 3 2 6. 9 () 26 .fl5 It lLBO 10.8.2 -~ _., 25059 15 r ·•· l 0 K -1 -10 -10 -10 -10 -2 -3 -4 -5 -10 -6 -1 -11 -11 i: -1 4 .5 -2 -4 -5 -7 -7 -7 -6 - l -2 -3 -7 -8 -7 -R -s -· 8 -2 -8 -8 - -·CJ 2 3 4 - -7 ·-9 -9 -9 -9 J -4 -7 -7 -7 -7 -8 -8 -8 i:; -t:_ -11 -11 -12 -12 I. C l 2 3 ii -1 -:l -4 -5 -(:_ -7 - l -· 2 -3 ~ FUd'S J it.J2 {t 8 .. 4 5 29. ·10 35.85 2 .. 69 Ut~32 29.85 24 .. 04 46e52 6 .. 12 FCJ\L j5.25 f-.J K I -7 1~6 .. 3E3 -7 -2 -3 1 2 2--) ~ 5 5 -7 -7 -7 -7 -8 -8 -3 -8 -ft 3 -5 -6 -7 4 - 1 -2 2 3 l-1 10.19 5 17.35 -8 -3 -4 -5 6 -9 -1 . l, 22.40 36.93 -9 -9 -9 - L. 5 -3 -4 7 33 .. 01.~ 6 08 l~ o O 3 24 .. 81 34,00 L 77 lit. 55 J0.72 23 .. 21 1t6 0 7 8 5.91 13 .. 85 13 39 9.35 7 ~ 57 -3 131. 95 J.3;). 73 -2 66.,52 6i3o 80 -1 51 .. 90 53053 0 41. 17 39 .. Lil 1 18.65 J.'3 .. 6't l 9 .,, 7 a 2U.61 2 3 3.01 6 .. 12 ii 14 .. 3 1t 13.69 : 26.20 2 5 .. 1-tB -: 1 6 .. 1t4 8.02 0 1., 8 5 Oo60 1 31..48 .30~1't 2 '10., 92 4 l. Lt 5 1t9 o 2J 48 ,02 3 It 7o72 9 .. 37 5 0., 54 3o2J 1 49 .. 71 5L02 2 24.,42 2 1t~ 28 3 6~20 7.0J. 0 /1 4 45.,18 <'.,5 .. 83 _c: r; l. ?.-o 8 7 l 0.., 3J :tO.t.tO - -- 4 -1 t. " 8 .. 6'.5 LL.56 1 7 .. 1 7 5 26,,53 11.:s1 10., 19 ti 0 ... 1S 13 .. 27 l l ., 6 l J.7 .. 20 26.51 -2 (; L;- .. j 8 1t . U 6 --6 -1 -6 -6 -6 -6 -6 -6 -2 -3 -2 -1 57.,:53 -•6 -E -6 -s 6 8.33 -7 .. 1 C l7,.i7 J -9 -6 6 •• l 0 - l 3 -10 -10 -10 -2 1, _-:;i -11 -11 _,, C 21.. 25 5 9 .. <t '-J 5 5. l 7 1 4l} e [) 4 -5 -6 2 3 l l •l9 2 t. 12 11. 71.,, l <) ., 2. 1t _., l1 5 L 2., Jl1 L 5 c 6 FtJBS Jlo 20 50 .. uo '~9.22 12.,40 l. 2. C9 32090 35 .. 75 0 I;; -2 -3 7 4.55 -1 -3 -1 -2 C -5 -5 -3 1 2 7lo86 10.J.3 51. 21 48.33 13 .. 70 5~64 32 .. 32 -5 -5 -5 -6 -6 -6 -6 -6 -6 -· 8 - 1 -c. -3 -4 _ r:: -, -7 -t, -(; -1 -7 - 7 -2 -3 -7 - t, -7 -8 -8 -5 -8 -9 3 4 5 6 1 2 3 4 5 6 7 3 4 2.20 4,.7J 23.63 54 o 1t4 16 • .l.3 6 .. 26 1.3.,3._1> 12 .. <t 5 3 1~ .. J 8 23 J 7 0 1 a .. 71 ~ 50.25 6 7 13.1-, 7 22.56 -1 s -2 6 - .3 -1 l5 1-HL 1t4 3 ;~ .. 5 3 -I _s:; _,, 26.S5 lt 8 ,, 32.97 3.27 -10 -10 -3 -5 -5 -4 -5 -6 -7 r CAL. O.S3 33..2.3 3 7.., 28 9 16 16 .. C8 0 2L 36 35 13 33 .. 22 0 8 .. 59 2.611 2 ti .. G 1 3. () 1 72 .. 06 12092 52~.3'~ 48.67 12 .. 56 2.79 31.93 0.89 .3 s 16 L3o72 55 .. 09 l 8. 9 2 5.C8 lL 69 11 .. 32 3 5..., 19 2l .. Lt 7 20 .. 20 49.cl0 l<l.,77 23.46 8., 76 U .. J9 7 ,, 9,. 7 8 29~86 23077 50. 11 2 9 ~ 12 2 Lt• 6 0 7 53.S9 -9 -2 E 2J..., 09 23,.G0 4 2. 5 6 l 0 .. ,J 6 •• '-1 -l -4 -2 C l 20.U., 10" 12 (J 1 9 .61 9 .. 18 ltt o 58 -Lt _-:i 5J.92. Jlo 1t3 20~83 -l1 -1, 3 -/1 -5 -6 -7 l1 5 4 • !t l J 1t • 7 -/ 2 L .-, (jO 5 e6 2 3 i t,. ') ·r 3 5 ,. l l 4- t~ ., 't /~ -4 -4 L 5 6 7.00 3Je'J7 3 11 .. d 7 1.3. J2 16 H K L FOGS FCAL -4 -5 -5 -5 -5 -8 1 -1 2 -2 -3 3 20. 15 15.73 75063 50 .. 32 21.:37 l.J.6S 7 3. iJ l 49063 - ti i:: -- 5':>.54 5& o l O -5 -6 -7 6 21.72 7 8 21..20 23.77 7., 8 L~ 6 .. 81 -1 I; -2 5 ') 6 - l; 7 2 (:; 59 .. 80 38 .. 69 71 .. 11 4.17 4.85 24-.,57 58 .. 03 36.75 71042 3.68 l.,J8 25.14 - '5 -5 -5 -6 -6 --6 -6 -6 - L1 23., 29 -7 -5 -1 -7 -2 7 25.01 25,.lt9 -7 -3 -8 -3 -3 -3 -1 -1 8 8 11.,46 l 0 .. 11 41.94 13 .. 50 10.28 -2 -3 --3 -Li -3 -3 -3 -3 -4 -~ _,t -4 -·'-t -c -7 -E -1 -2 -J -4 -5 1 2 90053 3 4 .,C: 6 84.41 27.39 53065 l3o76 ? f. 7o69 'l ~ ... 7 -1 -2 _--:i -2 -1 -1 -2 -3 -2 .. l -2 _$; -2 -·2 -3 -3 -3 -6 -2 -2 •• 3 -- 7 - 1 - ?. -~ _,, -L, --4 s 8. 8 8 2J .. 07 J. 7 ~ 53 15.83 -5 -5 -2 -4 -l1 0 0 0 0 0 0 0 0 0 -~ 1 -1 -2 -3 -/1 -5 -£:. -7 -8 -1 -1 -1 -1 -1 -2 -3 -4 -- l -5 -1 -6 -1 -7 -2 -1 -c.. -2 -2 -3 -2 - Li 17.., 15 -2 -3 -3 -3 -5 -1 6 -, e 7 8 9 9 2 ') 'i 5 l 7 f! 12.23 JL,80 57~53 57 ... 8 8 5,. 24 3oc4 4 .. 66 6~86 3., 16 2o 20 165.60 165 .. 76 65.,60 65.78 1t 7 .. 0 5 115.<;(~ 29.';-9 29 .. 00 J 1t,. 1 2 33 .. 65 8 o2 l 7.35 9., .35 9o2J 32 .. 05 -'t - 131 .. 49 r; ,2 '+ o 3 Lt -, J.O. 7 2 (: i6ol3 80 .. 39 15.26 tL52 79., 38 2 f.J-. 6 8 9 .. ,2 7 J. 0. J 6 -4 --2 -3 - 1 l l 9 1 7 l l 1 l l l C 8 c; C C 4L~ .. 1Q 6 -5 -6 -6 -6 f 7 8 -L1 28.59 lt 7. 4 l •• l •• 3 -4 52~94 -1 ·-2 -3 -3 28.54 46.23 15 .. 98 J. 7 .. 54 7 9.30 15.60 10.t.-9 -· L -· 5 22.57 FOB$ 10 .. r1 1-i·., 82 L}] o 6 !3 ✓ -£:. 13436 7o2J l f c; i:: ., -5 _cc; 52 .. 93 K -s - (:; 4 ·1 8 5 -4 -4 21 .. 23 5 0 .. 4 1t 38.,56 9 0. 9 '~ 83 .. 57 31. 07 H ·- 3 e 3.97 o.o 16. t3 6 6.36 9 12 23~52 ;> 18., 20 .16 .. 3 2 1,7~6() 4 o 2 1t 10 113.0<J l. 127.,9 1, lJJ .. 20 £ 137.:56 lttO .. 12 3 J.8.70 Ut,, 7 1 /1 16.59 19,, 07 5 3 1t., 9 J 3 /~. 'i 0 6 9.97 9.97 7 3.79 0 ~ 57 E 13 ., 66 13 .. 7 3 "l 1t5 .. 5 2 '~ 7,, C8 4 29 ... 62 27.85 i:: 12.69 9 .. 62 r~ 36.27 37~J4 7 1-t • 1t 6 L,81 ·e l7e3H l7,.C6 <; 1 L66 16,,37 r:. ., 2.64 0 ii 7 (:; 5lo76 51.62 7 59 .. 33 58.34 e l. 3.., 3 7 l 7. 19 <; 7 .. 33 6., i~s 0 t e (_• 9 -8 -7 - (:_ c -~ 5 4 l;6~6 1t FC1\l. -11 3 -3 -2 2 - l 1 10 .. 7 0 10~4-2 9 o L12 .Jlh06 11.12 L67 r~ s1 7 .. 72 6~27 JL1.., U3 37.LtO 11..37 2 6. 58 9.04 8 5 t;Lh 27 37~04 0 74.21 7'5 ~65 80. 6'1 5 1 • it~) 5 J. 15 176.11 17 1, .... Jl jl.,<.)9 36 .. 81 J0.09 30cUO l._ 7.., _It 7 2 (1ft 2.52 .l 0 d l!;.U9 tl. 5 7 81.'JO 0 0 <; - {; 0 0 0 0 0 0 8 7 -5 -L1 (.; _:, <; -2 22.3a56 225.11 -1 113.0t:: l.72.Sl 0 6--Ldl 60" 03 1, ·.) ,\JO 4 32 .. l. 3 .JJ~60 1 'l H 0 0 0 0 -1 -1 3 3 3 .3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 K L -1 7 ·- 2 f -3 -4 10 -1 -·2 10 g 8 7 6 ~ ~ 3 2 1 11 lC 9 8 7 6 - i:: 4 3 l 2 1 12 11 l iC 1 1 1 1 l l l 1 1 q 8 2 2 l 0 0 0 0 C 0 0 0 0 () 0 s F08S J ·J .12 15 .. 07 1t- o 6 9 FC ,\ L JJ.93 14 .. 6 l 0.70 22 0 09 22,. 22 s 29.03 2&.31 10 7.21 8.02 -7 U~OZ . 12. lJ. -c 42 .. 2 3 liJ,. 25 -5 24.61 2l;.68 -4 12079 12.u2 -3 33.03 34 16 -2 11. 87 7 88 -1 31 .. 3 1~ 2 9 .. S4 C 5d,.01 58~03 1 46.55 47.ti9 2 287.93 293~02 -6 JLto26 36 .. 03 -5 21o03 21.50 20 .. 4 7 20. 1t9 -3 17 .. 29 18 .. 82 -2 26.,09 27~57 -1 68040 67.63 C 35.05 83.77 1 71.51 7lo8l 1+9 94 2 48.62 3 7 .42 5066 4 6 1+. 9 8 65.2.3 - i: 34 .. 25 34.,C6 - I. 3.65 2 e 15 .. 2Lh83 23082 -2 52 .. 09 51.67 s 8 7 6 5 '1 ~ 10 l0 -7 15005 - 1 C l 2 3 2. 13 37oC0 ~ -c c -3 -1 J 1t o Lt 6 !. ·- 5 s 1to 31 ,, 20.63 8 3lt,. 5 7 72, 3 0 15.)2 l -2 -2 Y),. 15 11. L3 --4 -1 21., 24 8tt.90 '1o.30 i 6 ~ '> 6 23~59 27,.70 18 .. 01 0 t -2 -2 22.54 8 6. ·12 38.7.5 15.63 2L 72 27 .. 22 19 18 16 "0 l .. 3 -".l s 1 13 12 l l lC 79 .. 62 0 0 0 0 - ~1 6 -5 -4 .,r: 7 2.52 14 -2 ' [ 34053 42.64 5 0 -3 , 7.20 6 28.J5 -1 -1 -2 3ft. 8 2 41. o G8 L 19,. l 0 ~ 0 0 l 3 -2 -1 '" 0 0 1 0 - 1 FOGS 2 t) u 6 1t 36.JO -1 ·7 2 0 1 2 -1 ') 3 L 2 -1 0 5 I< 0 _,, 4 J H 0 l IL 7 J 7 2, 26 18~61 ZL 02 ld .. 78 6 L. 3 7 ()5.59 (,2420 -3 2 9 2 E 2 2 7 6 2 2 ,, 2 3 2 2 1 11 10 2 1 1 1 l 1 l l 1 1 1 1 0 0 0 0 0 0 0 0 0 0 i:: 9 8 7 -6 5 4 3 2 1 12 11 10 <; E 7 c 5 4 ~ ~ 6 5.20 20 .. 96 16.,53 7,. 7 8 38" 31 15~1 3 17.86 3.57 19.71 2o 76 18.22 J.7.62 30.93 - L~ 1 Qlh 46 -3 13032 -(:_ -5 -2 27.26 FCAL 13.83 JS.J6 18.73 27.S8 7 8" 't6 12066 21. 19 lo89 19.75 16.46 6074 38.,62 1 1t o 56 17.90 2 .. 1t2 19 .. 96 Oo45 18.39 19" 10 31.79 104093 10.53 26"63 -1 86078 86065 C 2i5,,5E 21 ~L 60 1 211...0(t 212082 -7 1L69 10 .. g i+ -6 .2.S .. -'d 2S,.06. -5 8 .2 6 7.20 -L1 UL,71. 17.66 -3 87.56 86.26 -2 162 o 6 L 159021 -1 86 .. 90 8 1+.S6 C 52 .. 4] 5 lo 5 5 l 37.59 33 .. 86 2 l't2.58 lft.3 .. 66 :: 36 .. 18 33 .. 25 -6 5.22 9.45 -5 21.26 19.92 -11 91.. 70 9 2 ~ 29 -3 8'5.50 85 .. 29 -2 20.91 20 .. 66 -1 60.9J 61. 13 C 3lo 78 3 0. 5 8 82.35 I 8 1t 9 1t 2 l l • 1t 1 12.06 93.09 92.78 3 O 0 2 11 6. 7 9 0 l 23.6l- 0 0 5 6 0 .J 11 2. 7, j<) 57 1t3. b5 4.'t. 0 18 r 0 C 0 0 0 4 4 K ZL 51 lC -(:_ 9., 1+8 s .. 2 5 4 4 I~ 2 1 1l lC 3 g 3 3 e 2 2 2 1 (:; 5 4 '.l J 2 1 13 12 11 10 2 s 2 2 2 -t 2 2 1;-,. 68 20059 7 '-j 7 11 .. 6 3 lC 5 4 3 2 26~56 1t., 3 d 4 3 28056 g (; 3 3 C 1 l 0 -1 4 3 3 3 '- 2 4 4 3 3 FC1\ L 37od6 LL 62 L 6 9 8 7 ,, FOBS 37,,27 l!t. 0 1t '.l _, ' 6 c; ., -" .J .• 4 -3 -2 6078 2lo22 _,, - 0 ,: _, 6039 -- Li 32. 9 1t 2 3 .3 7 1t4o09 62., 3 7 7 1 1~ 11-2 o'+O _'.) - t. - l C 1 2 '.) ,0 t ,: ~ 15 -3 l2olJ llo85 l ✓•• -2 - 1 1L07 13 .. 56 7 .. 18 3 .:, lit 38 0 0 0 0 0 0 0 0 0 0 0 5 5 5 5 r. _, 5 5 5 13 12 11 10 0 l 17.,Lr2 2 -2 36 .. 3J 58 .. 27 3.82 3't.. 6 3 '~4. 7 0 19 .. 65 12 .. 3 1 44.98 30 .. 08 U3.90 11 .. 7 1+ 10 .. 57 55 .. 1-t4 - 1 3., 98 0 It 7 • 1 7 s e 3 7 5 6 4 f: 5 7 e L1 3 <; 2 10 9 10 8 7 6 i:; ., -5 - 'i - ? -4 3 1,_ 70., 6ft 2 r:) 2 3 86~28 66.84 5 4 73. 5 8 - ,4 24.50 6.08 4o<;J 33., 59 4 l 11 22.90 4 lC -'.l 44.17 '+ <; 61-,,87 U o It 8 '+ -2 -1 e 4 i , C 1 2 lt 3 51.. 15 2 n .. es 37075 19 .. 75 2J .. C6 2 7 1, 2 12 .. -rn 10~33 3lo25 33.~8 26 10 4 3 1, It 2 1 13 ~ 1l 13 - '1 23.JO 3 2 9 18 0 0 0 4 l 8 7 3 lo 4 1t l:JO_,Jlt 3-1., 03 18~40 1 2 c s 27.06 l 79089 6 1 <; 2 5 2 2 C l 1 l 't ') -1 7 :, 2 1 7 23.26 Lt - ll IC F C1\ L 53 ,.86 33 • 9Li 32 .. Bl -3 -2 FlJt) S 36.,65 5lo96 Vi L 32.80 4 C "3 (:; 3 1 l l l 1 1 l l 1 1 2lc59 0 2 l 1t. 9 5 2lo99 22.56 -1 126 .. 70 126 10 1t3 » 8 !t 1t2., 5 J 0 l 53008 52 .. 25 2 61 .. 22 57083 ? 126.23 12 7.., 26 - !; 14 .. 72 14 .. 44 11-. 84 lo99 _? 2 8., lLr 27 .. 70 -2 58.24 56.., 29 l;L,.,67 - 1 1t7o06 C 83 .. 10 8 6 .. 85 43066 •t6 0 30 1 £ 5o59 3 .. 68 :. 72 .. 66 7 2,. 11 4 20.50 21.57 c; 15.80 17 21 t, '- 0 H 2(}o56 12 .. 02 9., 31 30 .. SZ 3 Li • ,:~ fl 2 1t ... 9 5 12.97 4 61.. 61 " 25 .. 63 (:_ 8nl7 0 0 12, 6 ':) 6L 55 2 1, o 9 l 6~28 4 3 20., 2ft 50 .. 71 80 .. 27 8~ 76 LL, 30 2::S., 03 Li 90 .. 32 60.39 I.. .__ 33,,97 - t, l :5. 2 0 12 11 lC -3 17.31 ·- 2 2 '1 .. 0 tt It 2,. 2 1 C) C -:, e 1 J 7 ?. J 6 5 .; J 13 .. 19 Jl.20 3 6 .. bl 20ol7 '-I 34 3 3 3 3 .J 'l ..I 3 3 J -2-~ -1 . " .,c J6 5<J~:Sl 0 33., 7 7 '~0.2-'t & 0 9 0 O 5" 16 19 ~ 13 37.50 5 7 .. 16 3.C6 35.01 I; 2 • (;4 19.40 1201.;'f 44 ... 02 29.99 l 8" 53 J. 2 l't 0 9 0 115 55.,12 1t o l 0 L19 ~ 6 5 7:J.33 84 .. 3"/ 66., 85 70.25 24.37 5 .. 8 2 2L 57 5L 3'> 79.,68 117.32 l2o-16 l '-J" o9 sa.66 () )_ ~ ~3 32060 1 11 o 20 15 .. 53 29.27 Ld. 86 13 .. ~b 2) .. 3 11 3 5 0 g 11 l O .. 6 Lt J 5., 2 3 60 ~ 20 J ,:>., !! -, J9J '.> 6 19 H I< 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 1 1 11 13 12 11 IC g L B --=l ..., -2 - 1 C 1 2 FOUS FCAL Ju.19 JL).78 't .. 6 3 29~26 3L07 33~73 19 .. 02 34~88 l S .. 53 '1 3 4 5 5 5 2 6 1 13 7 -3 12 1l -1 59 .. C8 i: (; 7 E 55.75 10.24 10 .. 95 4 4 s 54.71 9 74 s.,75 3., 79 5~84 10 6.,06 -2 16.,30 25067 27~35 6 .. 31 _ 15.11 2,, 1t 4 1-t 2" 18 15.83 30 .. 8 4 25.0J 27.. 8 1-t ~ 1-i· o OJ 4 4 4 4 4 4 4 4 4 4 3 3 3 15 14 1 <_; l1 1 l 1 1 l l 8 i:: 45 .. 85 6 7 lt 1t ~ 1 l 13 12 7 (; 42.17 l L Ott 30.,6 1t 5 e ,'1 <; "'.l 10 L 76 16 -1 12.75 0 Lt5 • 16 6 • .J 5 1 11 5 2 3o83 0 2.08 11,99 15 C Lh3 l Lt. 3 8 14 13 1 2 38 .. 28 30084 12 ") 11 10 r, 36.63 30~10 37.10 l1 3 3 3 3 3 9 8 7 7 8 (; <; 10 - l1 8.92 cl. 1,3 _ :i 3., 59 30 .. 11 3 .. 32 3 3 3 3 3 2 2 2 2 2 29.59 2 5.2., 21 56 .. 72 2 g E f:, 7 6 6 6 6 6 t ~ 2 .. 49 5 • lt 7 14038 5 .. 8 1+ i:; ✓ L1 ? 2 1 1l 5 (: -· ~ 67c6C 23., d9 5 5 513o94- 2 1 JS.08 25038 r. ~ tL27 69 26 c. Q /~ t 38.10 350133 6.75 23 .. 60 3201.2 13.60 3 .. 96 J l},'11 6 15 0 23.51 J2o ltlt 12., 10 3.ll 0 1 ~ '1 FC1\L 23 11 2 1t5~ 14 l r.: 7 FrJoS 2 2. ') 7 1t5. 3 9 C 5 , ·4 e - I n .. 1 11 11 8 ~ s L -2 22.,65 48002 11 10 6 ,:) K 10 7 6 - 1 C l 2 3 0 6 6 6 5 5 5 5 3.72 2 3 .. 11 l 1 l 1 l 0 0 0 0 0 0 0 0 0 0 L . 31 6067 H G. -2 G 48 22056 5. 2 l JU., 79 36.,87 4.97 6.,40 2ft.03 2lo02 41.. 2 7 3 .. 68 38 ~ l C 36.51 4 .. 48 8 .. 57 23 0 ~33 20 .. 96 1 21.02 u.. 36 40. 81.t ZiJ .. 77 B ➔ 04- 8 2 3 7. 6 6 37.61 7 ") 28 .. 38 (:, 4 5 6 7 8 29068 8.04 33 ~ 9 5 JJ.77 16.91 12.15 18.48 10 9 0 c:; ✓ '1 3 2 1 1 11 13 .12 11 10 9 6., 23 ll.65 Lt., 56 -2 -1 5,84 11.. 76 20.30 3 .. l. l 18.,ttS 1.79 C 36 .. 32 J6a05 1 2 22087 26002 5 .. 4 7 22026 s 3 4 10.C7 23033 J., 6 3 13-. 71 J. Jo 1 tt 7 t:: 1-t6 9 74 't7 -, 3?. t 6 ? 8 g 2J.77 23oc5 9., 3 0 17,, J6 l 8. l 0 lC 2L33 5 62 2 Oo 96 J. 5 14 13 12 .. 1 25 .. ::> 8 26 .. J3 0 3 • 1-i3 l 2 U.3. 5 l 31 , 66 L;-,, 43 16.08 31 .. <i 11 11 10 9 1 23.62 25.05 L4 16.78 16 .. 2<l t:; lclo30 39.60 2L 10 6019 9.69 15.7'6 8 t:: ✓ 'i J 2 6,, 98 7.69 0 -1 C l Lt.2 o 11 2 Lt2o7J 2 I 2 t,:>. i t3 1;-9 0 .J 2 2 6 e Jl.05 J (.). 't ;~ L1 1 ll .. 78 J. 11~89 Lt o 1t '-) '5 l) ... J9 -J ') • Lt f; 9 .. 05 2 i:; C 1 1 1 15 l't 13 1 5 /. 5 .. 06 5" 19 9., c; 7 J9 8 :.i 7 ? 3 <t .. J 9 3L.?0 , 52..B6 _5 li-.2l 2 e l 7 0 5 '~ Y -3 oLt7 2 l , <'t 3 ') 0 0 20 H 1 l 1 1 l 1 0 0 0 0 0 :< 12 1l 10 9 e 7 16 15 14 13 12 11 l. FOBS 4 22 .. 7 1 5 34.29 6 7 Ul .. 90 c s 2 '.l 4 c:: 21..37 8. 1t 7 6 .. 31. 29 .. b 0 1 J • L~ 9 l 7. 5 3 FC/\ L 22 .. 38 Yi .. 59 18.71 20.,76 H K L FOBS FCA L It 8 ~ 8 0 110 6 7 9 0 1J 7o32 4 ..,?. 7 6 c:: .., '-t c s 7 .. 24 10 . lJ 4.26 23. 1 0 14 3 3 3 13 12 11 l 2 18..,71,. 13 .91 35~35 3 10 3 4 5 <; 6 2 1 .51 8 9~47 l L 46 3 3 3 3 7 8 15. 77 2 14 29. 13 3 1t . 69 2 2 2 13 12 11 17 .66 1 6.89 5~55 8. 15 19.73 4.79 2 lC 2 8 8 8 8 3 8 8 9 1.84 3001 0 14 ... E 4 1 7 099 28.78 27o 1tO 2. . 23 7 '.l 4 29 .. 31 27.96 5s08 9o 2 0 10 .. 75 l :>..,99 27 .. 95 35.79 56-o 56 13. 70 37.03 2 7 .16 7 7 6 6 6 2 l 11 10 C: .., 22 ., 53 21. 93 0 ·6 7 0 7 7 7 10 10 c; -3 e - 1 7 7 0 7 7 7 6 5 1 1, , C 6 e 8 -2 2 3 l 7., 09 1 6 'i9 l i h 1t 11- -1 22 .. 60 39.68 lLh 50 22056 0 1 7 (; 6 6 6 5 .4 't , 6 2 6 1 5 5 12 11 E "i E -1 0 5 lG 5 5 2 3 5 1 2 3lo65 30088 3 . 78 2., 88 9004 L 71 22.,Sl 23 .• 30 6 7 ~ 7 'i 4 16,. Lt5 ld. 6 8 t.12. 80 21.02 33.69 .32 .. 21 1O.4t3 l. J. 2 9 7 .. 72 e 6 5 5 5 3 8 J. L 09 5 4 2 s 5.18 13 C 4.52 1 4 12 11 31.49 2·~-~5 l. 32. l J 3 9. 7 1t ,, '• ft 27.2 0 (; 6 9 0 36.115 -2 c 5 5 5 5 57.82 1 J. 59 lC 2 3 9 /i 0 38.62 16,5 7 ,, ,, l1 7 6 10 s E 7 s 3 4 c:: 6 7 8 -2 -1 C 6 l 2 c; _, 3 Ii t. ".l _.., I; 7 • 2 L1 30.,84 1t o Q 3 8 .. 4-8 4.57 1 7 *93 9<> 0 7 z6. 1,-6 55 .6 8 4., 7 7 7., 36 23 .. 13 20 .. 1'1 1 1t.l3 35.32 29$87 1.. 36 21. 82 1 B. 19 l 7 .. 19 7 .. 09 9 0 1t6 20 .. 6 5 0., 62 10. 7 ft 5. S 6 1 6 068 8.,, 0 1t 26,. 70 39 .. 25 55,,94 39 .. 02 4 1 .. 7 7 7 .. 31 2,, 6 5 25. 9 3 2.:., .. 7 3 ll.. Id 4 J. .,.:) Li 6~66 L98 .26. 22 ;~ !~ ., 3 9 10,. t '.5 19. 18 a i ;2 ~ 55 8 8 2 l JL, 29 l 2J.S7 7 11 7 -1 22D66 23038 0 ~ 8 1t 0 .. 65 7~99 7 7 lC C 26.89 2 8. :.l l g 8 1 30 6 3 JO~SJ 2 f;.Lt,.2L,, 1t l t . 7 -;i 6 4 c:: c:; 6.99 31,, 3 2 Jo56 3?.$13 l)" l l1 • 3 2 7 e 22.56 3.29 27,70 220 06 3 ... 07 26,. (iS 1 c_; 19 8 7 12 0 19. 2 ' t 1l 10 1 17.53 ltL86 2 O o l 1i 19 .. 6 7 1 ·1 .. 1, l 1 iL 011 lt., 'i 0 22 .. 06 <'. 2. .. 2 't 20.71 JJ.56 32 .. 39 l?..9J 17045 6. l l 10.18 2.09 7 7 7 7 7 7 7 7 6 6 6 6 ,, 6 2 0 0 -:i "/.,56 6 ~ l L1 2 5. '> () 16.J\.) 2 >3 ~ f-t L/ J 2 • 11 '.i 1/ .. ::,5 0 ~ (; 2 2 ') ., 7 9 6 6 8 7 s 2 1+.{i') 16 • 1+ ~) 25~22 6 (: €:. 2d.07 32 6 6 c-:., 7 J 1 " J f, 't f: 17., 5 B '.;2 4 0. ,, l J9dL s I., 0 7l 21 H K 6 3 1~ 5 5 5 5 5 5 5 5 4 4 4 -, 6 6 6 10 10 13 .. 2 0 5.18 3o75 3 10 g '• "- e t 7 7 8 3 I.. 5 •E 6 g 7 7 7 7 7 '7 l 1 3. 1t 6 12,01 l1 '9• 8 8 8 8 FCAL l11-oJ2 2 4 8 8 8 8 F Cl (3-S u 13 12 11 10 9 9 9 9 9 9 9 9 L c; 11. 06 19 .,2 3 20 o (> l 17.,80 25.75 8 1 7 L. .t 3 4.4 7 ll 3 .. 10 22.33 30.6J 26. 6 't 24.22 7 .. 0 5 7 .. 39 t:; _, It 30.54 -4 5 2lo 73 -:: t 4<'to 06 2 1 7 8 16,. l12 lC l 8.16 6.31 20.64 2 5 .. 11 12. 5 5 2L63 2L 14 8 .. 62 5.31 12.,, 3 7 2L85 16 .. 76 11 . 2 1t s - 7 0 s 2 8 3 4 7 6 5 Li 3 11 5 6 7 8 2 3 10 9 4 8. 7 5 6 t 7 f. 5 11 lC 9 8 7 I; r. - c 1t"' 3.91 29.54 9.., 2 8 19 .. 18 21.93 <J .. 00 0 3.22 Oo87 21.93 31.. 09 27023 23.25 6,:, 35 7.16 30.'36 20.83 4Lt • 4 7 16. rr 3ocl 9.13 6 .. 2,5 19.33 24.12 J. 3. 13 2 Oo 9'1 19.32 7o79 6 .. 00 S ,; 8 5 21. 7 1t 16 .. 60 10.88 J0.57 10~31 .1.9,,35 22.77 d • 't7 6.55 .. () • 8 '• -- 26.39 27.S6 .l 3. 1t 8 l 2. '• 7 l Lt 11 C l O. l J 13.47 '1 J. '-to \JO r. 5 4 J (-_ 13.08 l5o0.?. 10.32 g c; 8 7 6 23oS3 7 98 ') 6 9 9 0 <- 10 10 10 10 Q 2. 11 3~13 10 ., 57 19 63 1 ·) . 73 15090 7 3 l.LoO I, l.L 75 ~ l 7.1.3 l tl. 8 0 ,, 6 O 1 2 .. 63 .l 7 ~ 17 '). L)l) ?.2 Cr(CNPh) 6 , determined as Nujol mulls or in HCC1 3 solution show a sharp band at about 2005 cm - i and an extremely broad band at 1 15 1950 cm- • Thus, although the precise value of the deviation of the MCN bond angle from 180 ° may be dependent on crystal packLng forces, the fact tha t the bend is electronic in nature seems assured by the similarity bel-v;een the solution and solid state spectra. The 1 broadening of the ii(CN) band at 1950 cm- is also explainable in terms of the structure since pseudo rotations along the M-CN--C bonds should be of very low energies. In fact, a low temperature IR spectrum of Cr(CNT>h) 6 in a KBr pellet shows the band at 1950 cm-· 1 sharpening considerably. Similar arguments obtain for the I\ifo and W complexes. The ramifications of this bending in terms of the electronic structure of the complex will not be discussed at this time, but will appear in a later section. By changing the steric requirements of the phenyl rings by putting large alkyl groups in the two ortho ring positions, one should be able to perturb the M-C-N bonds back toward coli.nearity. Strong evidence suggests that this is the case for Cr(CNiph) 6 (CNiph = 2, 6-diisopropylphenylisocyanide). The IR spectrum of Cr(CNiph) 6 shows hvo bands in solution and in the solid state, but the bands are considerably sharper and the higher energy band is much weaker in intensity relative to the low energy band. The spectrum of W(CNiph) 6 ,which is almost identical, is show11 in Figure 4. Molecular models show that the bulky R groups of Cr(CN1ph) 6 should tend to push the structure band to Th via nonbonding steric 23 Figure 3. IR. spectra of Cr(CNPh) 6 as a KBr pellet. Top curve T = 14 K; bottom. curve T = 310 K. 24 Figure 4. Upper curve, IR spectrum of \V(CN1ph) 6 in HCC1 3 • Lower curve, L-q spectrum of V✓ (CNPh) 6 in HCC1 3 • 25 interactions among the i-propyl groups. The idea that Cr(CNiph) 6 is closer to Th symme try is also supported by the simpler appearance of its electronic spectrum compared to CrCNPh) 6 • Useful correlations of the appearance of the ii(CN) region cf the IR spectrum of M(CNAr) 6 complexes with the microsymmetry at the metal are apparent. 0 In Figure 5, the infrared spectra of Cr(CNPh) 6 ' +1 +2 ' are shown, and in Figure 6 are spectra for Cr(CNPh) 6 , Mn(CNPhCH 3) / , and Mn(CNPhCH 3) 6 2+ • Other IR spectral data are given in Table 8. Thus it appears from the data presented that for a given metal, oxidation results in a sharpening of the ii(CN) stretch, an increase in energy, and a lessening of distortions away from Th symmetry. 6 For the isoelectronic d metals (Cr(0), Mn(I), Re(I), Mo(0), W(0), Fe(II)) it is seen that moving to the right and down in the periodic table, the M(CNR) 6 complexes tend to deviate more from Th symmetry . This is consistent with an increasing propensity of the metal toward distortion to relieve the instability caused by increased electron density at the metal which is caused by a gradual saturation of the CNAr 1r * orbitals' ability to accept electron density through 1T donation from the metal. 26 ;)., -. Figure 5. Curve 1: IR spectrum of Cr(CNPh) 6 in HCC1 3 ; Curve 2: IR spectrum of Cr(CNPh)/ in HCC1 3 ; Curve 3: IR spectrum of Cr(CNPh) 6 2+ in HCC1 3 • 28 T;;tble 8. Positiomf'of v(CN) for Several Six Coordinate Aryl Isocyanide Complexes 6 1 d Complexes ii(CN) in cm- Cr(CNPh) 6 2012 s, 1965 vs Mo(CNPh) 6 2012 s, 1960 vs \V(CNJ?h) 6 2013 s, 1962 vs Mn(pCNPhCH 3) / 2038 vs, 1990 wk Re(pCNPhCH 3)G-r·b 2070, 2040 wk Cr(CNiph) 6 2005 m, 1962 vs Mo(CNip h) 6 2000 m, 1960 vs W(CNiph) 6 2000 m, 1960 vs 5 J (CN) in cm- 1 d Cornplexes Mn(pCNPhCH 3) 6 2+ 2160 s Cr(CNiph)/ 2065 vs M:o(Cr-n:ph)/ 2050 vs W(CN1ph) 6+ 2040 vs a This work, unless otherwise noted. b M. Frei:ni and V. Valenti , Gazz, Chim. Ital.,~' 1352 (1961). Electrcm ic Structure The Electronic Structure of the Lir;anas . . _, . ~ ~-.,.~ ~ ~ , , . . ._,,,.....__)-,~,,,..._ ..... ~ 5 23 Simple m.olecular orbita,l calculations ' have be.~en ca rried out on methyl 5 vinyl, and phenyl isocyanides. The impo r tant asp ects of the elecl:ccnic structure of th es e molecules are that the y contain a lone pair of electrons localized on the carbon atom. which can form a strong CJ bond to a transition metal and that they Rll contain two CN 11 * molecular orbitals which can be potentially us eful i.n 5 formjng drr-r,m* 7f bonds. The calculations sho\v that for aiky1. isocyanides, which ha.ve cylindrical symmetry about the C>-=N bo.'.1d, the b.vo 11* levels are degenerate as in cyanide ion. Phe ny 1 1"c:<or•y~111·de ho•ur.--,rer -.L ~ IJ V (.. ,., ~ .. - 'lr, \:;; - ' In vinyl and tho pl-::in a 1·i~•.\..J' ~-n of ,--.11·1-R '-1 ....., th ~• o se.. grn1; p t:: ,, ,._"",,i:"; . ,,,._ t., -,i=i - • il,.,.A.J.."-' ...._ ~ _.. ..-. ... .....,1,.. '\.,: ,_ ~1 . . • ·" degeneracy of the 11'~ levels so as to stabilize one (';T* vertical) through interaction with other p orbitals of 7T symmetry relatiyrn to the other (1T* horizontal). Thus in qualitative terms, takb1g phenyl isocyanide as an example, 1r* v should be a nmch better acc eptor * . than 11 11 since it should be able to allow electron density to escape 24 into the phenyl ring. This is in agreement with 1-Iorrocks' work which puts p-tolyl isocya.nide above t-butyl isocyanicle jn respect to forming 1r bonds. Thia effect "\}_ ill be quite import.ant in the 1 discussion of the complexes which contain phenyl isocyanidc. 30 6 The Electronic Spectra of the d Systems ~ ~ , , _ , , , . . . . , _ , , . ~ ~ . . . . _ r ~.~,...,,_;---. .,~,......._ Each of the complexes M(CNA.r)G [Iv1 ~-= Cr(0), Mo(0), W(0)] exhibits strong electronic absorption bands above 300 nrn. bands below 300 nm are attributable to 1T 25 primarily in the ligand system· The 11* transitions localized and are not of primary interest. Spectral data for the observed bands of M(CNAr) 6 (M = Cr(0), M:o(0), Vl(0))ai1d Ar = Ph, 2, 6-dimethylphenyl = Dph, 2, 6-diisopropylphenyl = Iph; and 4-chlorophenyl are set out in Table 10. In Figure 12 , a molecular orbital diagram was constructed assuming the idealized Th symmetry for M(CNAr) 6 complexes. This diagram was constructed by estimating the interaction oi the highest occupied and lowest unoccupied molecular orbitals of six CNPh ligands with the central metal. The ground state for each complex has the (tg) 6 1 Ag configura- ti.on. As is the case with the related M(CO) 6 complexes, 2 0c the lowest energy excited states are derived from either ~__-d (d7T - da*) or metal-to-ligand charge transfer (MLCT) transitions. It can reasonably be assumed that the d-d states lie above 25,000 cm -1 , and transitions to them should give rise to relatively weak bands. Therefore, it is not likely that any of the intense bands in the M(CNPh) 6 complexes are due to ~-~ transitions. The situation regarding MLCT transitions is more complicated than for the M(CO) 6 complexes. As has been previously discussed, 5 molecular orbital calculai:ions suggest that there are two low-lying 76.2 46.0 55.8 57.6 31. 5 81. 0 55.6 25.2 31.1 43.5 21. 0 26.2 32.2 40.0 42.7 21.5 27.2 31.7 40.0 42.7 397 321 230 475 382 311 250 234 466 368 315 250 234 \V(CNPh) 6 Ivio(C1'.7h) 6 65.6 21. 0 476 Cr(CI',IPh) 6 55.6 54.8 65.6 35.0 35.5 40.1 iimax'kK Amax' nm Complex E X 10- 3 Table 9a. Electronic Absorption Spectraa of M(CNAr) 6 Complexes ,:, L v· "h * L 11 Ti v * L 7i V *L in traligand intraligand d7T - "h* L V riv* L d1r -► 7T ,;: L d1T - intra ligand intraligand d7T - 7Th,:, L d11 - drr - '!Tv *L intraligand d1r - d7T - d7T - Assignment ;...i CJ-' Cr(CN1ph) 6 \V(CNDph) 6 Mo(CNDph) 6 Cr(CNDph) 6 Complex -- 47. 0 39. 7 73.9 31. 5 41.0 22.0 25.8 31. 9 38.9 21. 9 26.2 31.4 38.5 21. 0 24.9 32.0 41. 3 317 -244 454 387 313 257 457 381 318 260 475 402 312 242 - - 66.6 24.7 405 47.6 64.1 26.1 76.0 61.7 -- 54.8 85.6 39.9 55.9 -- 42.6 37.0 48.0 21.5 465 E X 10- ii max' k..T< ;\max'nm Table 9a (Continued) 3 1T V *L V *L 1Th *L 1T in traligand d?T - 77h * L d?T - dr, - Lrt raligand d1r - 7ih * L d11 - rr V *L • drr - 1rv*L intraligand d1r - 1rh*L d7i - d1r - 1r V *L intralig-a.nd d.rr -· 1T h * L drr - rr V * L V d1r - 1r ;< L Assignment t-v w Cr(p:NPhC1) 6 Vl(CNiph) 6 Mo(CN1ph) 6 Complex 37.0 85.7 23.0 26.0 32.3 40.8 19.2 21. 6 23.0 26.8 32.2 35.3 40.0 20.7 24.5 30.8 41.3 435 384 310 245 521 463 434 373 310 283 250 484 408 325 242 68.1 36.4 66.0 58.0 -41. 8 44.3 44.3 60.0 48.6 -74.5 79.0 34.1 51. 3 71. 6 21. 0 1_Q -3 475 EX iimax' kK \max' nm Table 9a (Continued) 7i 1i V V *L *L 1T 1T 1T 1r V V V V *L *L *L *L 1T 1T V V '~ L *L intraligand d1r - ?Th *L d1T - d1r - in tralig-a.nd intraligand d1r - 7Th *L d1r - d1T - d1T - d1r - intraligand d1r - 7Th *L d,r - d1r - dr, - 1r V *L Assignment w w -- 66.8 36.6 80.1 31.2 39.4 21.2 26.5 31. 6 39.4 321 254 471 378 316 -LI. 2;L 63.4 53.9 50.6 81.2 25.7 389 10- 3 42.6 E X 20.9 iimax' kK 479 Amax' nm 7T h * L V V *L :* L n intraligand 7i 7i d1T - rr, * L drr - drr - intraligand drr - d1T - rr V *L drr - rr V * L Assignment a Extinction coefficients measured in THF at 25 °C in a 0. 2 nm cell (E ± 10%). W(pCNPhC1) 6 Mo(pCNPhC1) 6 'Complex Table 9a (Continued) w ,,J:,,. 22.4 27.2 8 1.3 40.0 29.4 31.1 40.2 42.7 44.4 - 446 367 320 250 340 sh 322 249 sh 234 sh 225 - W(CNPh) 6 c [Mn(CNPh) 6 )CJ< [Mn(CNPh),] [PF 6 }i c. r 4.6 - 61.0 66.0 51.0 71.0 75 .0 - 58.0 41.0 44.0 d d d d 46.0 73.0 36.0 tmax X 10-3 548 490 345 325 250 235 18.2 20.4 29.0 30.8 40.0 42.6 21.4 24.7 26.3 32.7 40.0 21.3 25.3 32.6 40.0 470 396 307 250 467 405 380 306 250 20.8 23.9 32.6 Vmax• kK 480 419 307 )_ma,c, nm 77°K• 5.3 6.4 - 46.0 46.0 - 46.0 35.0 42.0 78.0 53.0 81.0 36.0 61.0 23.0 3 t~ax X 10- o(CNPh)-,d, V. M-+:r (CNPh) <h-+:r.• (CNPh) intralig and d,-->:rv • (CNPh) d.n-->:rh. (CNPh) intraligand d,->:rv'• (CNPh) <h-+:rv • (C01Ph) d,-->.irv• (CNPh) d,-,;rh • (CNPh) i:it raligand d,r-->.i:v • (CNr h) d,-->;rv• (C NP h) d,-->Jl'h. (CNPh) Assignment • Spectra corrected for solvent contraction . b I: 1 isopcntanc/diethyletha solution . < 8: 2: I eth a no l/m ethanol/die th yl ether solutio n. dS o lutions were too photo5e nsitivc to allow measurem en t. •EPA ~oiutio11. 1 Ul truviole t spectra arc not rcportc J, owing to interfering l!bsorpt ion of the nitric acid added to the solutions. 20.4 22. 1 26.5 31.9 39.2 453 sh 378 313 sh 255 sh Mo(CNPhJ~c 490 21.8 25.4 32.3 vmax• kK 458 sh 394 310 -lm•x• nm 300 ° K Cr(CNPh) 6 b Complex Table 9b. Electronic Absorption Spectra of M(CNPh) 6 z Complexes C;7 c,:, 36 Table Sc. Electronic Abs orption Spe ctra a of M(CNAr) 6 Complexes Complex Cr(CNP h) 6 Mo(C NP h) 6 W(CNP h) 6 Cr(C NDph) 6 \V(CNDph) 6 Cr(CN1ph) 6 V/(CNiph) 6 max , nm ii 1nax' kK Relative Absor banc e 469 21.3 0.71 420 23.8 1.00 474 21.1 0.66 408 24.5 1.00 385 26.0 0.87 540 18. 5 (triplet) 0.08 425 sh 21. 0 0.59 470 21. 3 0.63 459 sh 21. 8 0.59 402 24.9 1.00 379 sh 26.4 0.92 470 sh 21. 3 0. 27 410 24.4 1.00 510 19.6 (triplet) 0.05 460 21.7 0.19 387 25.8 1.00 482 20.7 1.00 422 23.7 0.57 508 19. 7 (triplet) 0.35 469 sh 21. 3 0.99 461 21.7 1.00 432 sh 23.2 0.77 360 27 . 8 0.53 A 37 Table 9c (Continued) Complex Cr(pCNPhC1) 6 Mo(pCNPhCl) 6 W(pCNPhC1) 6 \nax'nm iimax'kK Relative Ab.sorbance 488 20.5 0 .70 435 23.0 1.00 483 20.7 0.63 420 23.8 1.00 391 25.6 0.76 552 18. 1 (triplet) 0.11 494 sh 20.2 o. 7"-1 480 20.8 0.80 470 sh 21. 3 0.78 414 sh 24. 2 380 26.3 1.00 38 Figure 7. Electr onic absorption spectra of Cr(CNPh) 6 in 1:1 isopentane/diethyl ether (-), Mo(CNPh) 6 in 8:2:1 ethanol/metha nol/diethyl ether (---), and W(CNPh) 6 in EPA(· · ·) at 77 K. 39 0 0 0 0 (\J LO A ·o ,,., _,._ -~~ 0 0 L() (\.j ,--:.., J 0 0 - f0 0 0 f{) _ _L___ __ _.,___ _- ' - - - - - - ' - - - - J_ _ __,___ _ 01 o ro 0 w 0 ~ 0 ]JNV8c!OS8\J (\J 0 I E: ~=~ 40 Figure 8. Electronic absorption spectra of Cr(CNPh) 6 (-1, Mo(CNPh) 6 (- - -) , and W(CNPh) 6 ( • • ·) in degassed THF (-·-·-) at 298 K. 41 f_P:•~ \: ~ : . ' / 7 J ~ -.·} r:-:,) I" ·- ·~ 0.:_9 'i .J, l., .•; I ✓-:✓ ~--/ . ,,. ,;.,:-::.,~....... .. .···• ... ·•• . .. ,.. ,, ;' • ' ,_.,,. • I J .•· r' -- _. .....,, ... -- ......... ~ . ,. _ i \ .\ 42 Figure 9. Electronic absorption spectra of Cr(CNDph) 6 (-), Mo(CNDph) 6 (---), and \V(CNDph) 6 (· • ·) in degassed THF (·-·-·) at 298 K. 43 .... ----- --- -- -... ... - -~ ... .. .. .... .... -... ..... . .·•• '' ., . ,, ., ' , ,,, f \ L --·--- -----·- ... -- --- 44 I ' I l l {;~ I ·:' :'~ ') \./ -~ f~~j \ \ \ \ \ \ \ . ~ \\.,_,,,. .....·-\ ,·- ·-. '•~( ~(~~ . ~\::.:--,;\;,-) - .-•_-.;..- .~ .. : · j Figure 10. Electronic absorption spectra of Cr(CNiph) 6 ( - - ) , Mo(CNiph) 6 (---), and W(CNiph) 6 (···)in degassed (-·-·-) at 298 K. 45 Figure 11. Electronic absorption spectra of Cr(pCNPhC1) 6(-), Mo(pCNPhCl) (---), and W(pCNPhC1) 6 ( • • ·) in degassed THF (·-·-·) at 298 K. .. • ·. .. . ... ... .... - ........ .. .. . ... ... :· \ \ I ' -/ I \ \, -·(;.) I< \TD) .-· \ ,, I . 47 .,1.. 7<'(Cl\!Ph) c ______, d?T 1ZllJ71117J221 a-(CNPh) ~ --------Figure 12. General classification and estimated relative energies of the molecular orbitals in M(CNPh) 6 complexes; d7T and a(CNPh) levels are occupied in the ground state. 48 7T* levels in CNPh. The out-of-plane rr,:' (CN) function is involved jn the lmver le vel, which is designated n ..,/ in Figure 12. The 7T v * MO, therefore, is sta bilized by conjugation with the 1r orbitals on the aromatic ring, whereas the in-•plane orbital, 1r h *, is localize d on the cyano group. The two lowest bands above 300 nm in each of the M(CNPh) 6 cornplexes may be assig11ed to allowed components of the tg -► tu1r v * (CHPh) one electron transition . The fact that these transitions are substantially blue-shifted in the electronic spectrum of the (d7T) 6 complex IV.1:n(CNPh)/ confirms the MLCT interpretation. The lowest d1T ..... 1T/' (CNPh) band, for example, is 8kK higher in Mn(CNPh)/ than in Cr(CNPh) 6 • The magnitude of the shift is very nearly the l l same as that observed for the lowest A 1 f!. v Cr(CO) 6 (35. 7 k...'K) and lVm(CO)/ (44. 5 kK). Tiu transitions in 26 The 33 kK band present in the zero valent complexes could be assig1.1ed as a higher energy component of the tg -- tu 7T v *CN transition but is more lo gically assigned to an excitation to tu1rh*CN based on the following argument. Comparing the position of the 8 lmvest IVTLCT bands in Mn (CNJ\1'.e)/ 8 • to Tvin(Cl{Ph) /, one finds a red shift of about 1.0 kK (43.1 J.{._;_"t( vs. 33.0 kK). Attributing the entire shift in the MLCT band to the position of 7T*CN and assuming that the 7T*CN orbit1..ls of methylisocyanide are good models for 7Ti/' CN of phenylisocyanicle, one predicts the tg -- tu7T h* transitions of Cr(C:NPh) 6 to be locat ed ctt or above 31. 8 kK ;,vhich is very close to the 33 kK band found in all the M(CNAr) 6 (M = Cr(0), Mo(0), W(0)) 49 complexes. This view is further strengthened by the spectrum of 7 Cr.(CNvi11y1)} which is similar to Cr(CNPh) 6 except that the two lowest bands are shifted to higher energy while the highest band is again found at about 33 kIL This is exactly as expected since the 5 stabilization of 1r v *CN conjugated to a vinyl group has been shown in calculations to be less than that conjugated to a phenyl ring. The spectra of the W(O) complexes show more complexities, containing several additional we2.k bands not found in the corresponding Cr(O) and Mo(O) complexes. It is nerfectly reasor.-:tble to assign these bands to transitions which have in creased in allowedness via the increase Ln the spin orbit coupling in W vs Mo and Cr. To call the transitions singlet triplet transitions though seems rather dangerous in view of the work of Crosby, et al. 28 , 29 on Ru(bipy)/+. They 6 have developed a model which treats MLCT transitions in d systems 5 by weakly coupling a d low spin core to the excited electron which is placed in the appropriate ligand orbital. In its limits, this model predicts that the singlet and triplet MLCT transitions are degenerate 2 when e /r .. and 7T are zero. Crosby's analysis of the luminescence lJ 2+ arising from Ru(bi.py) 3 suggests that off--diagonal matrix elements due to spin orbit coupling are larger (~ 1000 cm -i) than those due to 2 1 the e /r .. elements (100 cm - ) involving an electron on the ligands lJ and the ct5 core. Thus assigning spin labels to the various states arising from this analysis has little justification except for determining the allowedness of the transition. A more complete discussion of the comparison between the M(CNAr\, (M =Cr, Mo, W) 50 and M(bipy) 3 2+ (M = Fe, Ru, Os) is included in the section discussing the emission results. Up to this point, the electronic structure of the M(CNAr) 6 complexes has been discussed in terms of idealized Th symmetry. Crystallographic and i._nfrared data show however that the M-CN linlmge in Cr(CNPh) 6 is bent to 173 ° lowering the symmetry of the complex to S6 symmetry. The data suggest that the distortion is also present in solution since solid state and solution IR spectra are identical and consistent with S6 symmetry. The observed distortion can be rationalized in terms of a second 30-32 order Jalm-Teller distortion of the ground state which can be formulated as follows. The second order Jahn-Teller effect states that the energy of the ground electronic state is given by E = E 0 + f 00 Q.1 2 where E 0 is the energy of the unperturbed wavefunction 1/) 0 , Qi is the normal vibrational coordinate and f 00 and f0 k contribute to the force constant of the normal mode. The constant f 00 consists of matrix elements containing 1/) 0 only, but f 0 k is of the form au 2 ~[ < I/Jo I~ 11/Jk>] /(Eo - Ek) k Consequently, for matrix elements of this form to be non-zero, the direct product of r 0 1k must contain rQ. Thus a normal vibrational mode of proper symmetry rQ can mix the excited state 1/Jk into the ground state 1/) , causing a ground state distortion in the normal 0 51 coordinate rQ . provided that the energy gap E l -1 (less tha.n 30, 000 cm 0 - Ek is small • and that the excited state which is coupled to the ground state via this m echanism ~ti. distorted. MLCT excited states ca,n be e),q)ected to be substantially via bending of the M-CN bond angle to relieve the electron density build up. For a molecule M(CNPh) 6 constrained to have perfect Th symmetry, the ground state will be (t g) 51 6 1 = 5t A g. the lowest excited 1 1 l states are MLCT states (tg). {tu) and (t g) ~: g J (2 Tu + Au + E u and 1 1 1 5 t 2 Tg + Ag+ Eg), respectively. Since the (tg) tg, one electron excitation corresponds to exciting an electron from the metal tg orbitals (which are bonding) to the tg 7T* orbitals (the Rntibon<ling analog of the metal tg) a distortion along a tg, ag, or eg normal mode is parity alluwcd. The mode along which the ground state is distorted is the tf! symmetric bending mode which simultaneously 0 reduces all the M-C=N bond angles. Thus the data are clearly consistent with the operation of this mechanism. Further evidence for the occurrence of a second order JahnTeller distorted ground state is obtained from the temperature dependence of the uv-vis spectra of M(CNiph) 6 and M(CNDph)r, which are shovm in Figures 13-16 . The spectra of these complexes in 2 MeTHF or 2 Me pentane show drastic changes in intensity in cooling to 77 K,suggestive of some sort of gross structural changes. 32 33 As has been previously noted in the systems, , cha. nges in the h'> JL.l Figure 13. Electronic absorption spectra of Cr(CNiph)G in 2;..l\t1ethylpentane at 77 K (upper curve) and 298 K (lower curve). 53 .,!,. ·.~~" "<.-~·:·:~J !1 \ !•.:.:] Figure 14. Electronic absorption spectra of Mo(C:t--.Tiph) 6 in 2-Methylpentane at 77 K (upper curve) and 298 K (lov-B r curve). 56 speetra with temperature such as these are also consistent with second order Jalm-Teller distorted ground sta te. Based on simplistic argum2nts from the spectra in Figure 15 it appears that the structure of the complexes containing CNDph become less distorted on coolin.g while those of CNiph become more distorted. Both of these cases as well as the case where no change is observed (Ar :.::Ph) have previously been observed in other systems~ 1- 33 Low temperature solution infrared data would be especially helpful jn accessing the structural changes which a,re occurring on cooling in these 1Vi(CNAr) 6 systems. In vj ew of the complicated nature of the spectral details involved L.1 assigning more specific labels to the various electronic transitions present in these systems it would not be warranted to pursue assig11ments further without data of more detailed nature. Of major importance here is that these ambiguities are recognized and could be resolved by expand mg the simplified mcdel presented. Further experiments designed to elucidate the electronic structure of these cmnplexes are in progress. 5 The Electronic Spectra of the d S ~ 2+ + The spectral data for J\1n(CNPh) 6 and Cr(CNiph) 6 are gi.ven in Table 11 . 5 12 shown ' The ground state of both of these complexes h~rn been 5 to be low spiJ.1 (tg). The low temperature spectrum of [ Mn(CNPh) 6 ] (Pli\) 2 exhibits a structured low energy system (18. 2, 20, 4 kK) attributable to the LMCT transition a(C1'.1Ph) - tg. Similar 57 (\ \ I' i I i !i \,\//' i I t- t :'.-_ ! :._,;0 i 1· I ' \ \ \ \ \\ · ~ . Figure 15. Electronic absorption spectra of Cr(CNDPh) 6 in 2-Methylpentane at 77 I< (upper curve) and 298 K (lower curve). 58 1"\ I' ! \ I I I i \ l I \ \\ \ I . II II I i L \ \) '.: _:.j :~ • I I .~, ·~ :" <: ;J I <.~: _,,.,\ .:-:--.\ ,:.~-..: -.. ~ j <. .:/ Figure 16. Electronic absorption spectra of Mo(CNDph) 6 in 2-Methylpentane at 77 K (upper curve) and 298 K (lower curve). .-:.. ,·-,. .~-:-:,. ~~ ~~· · ·.;.__.·} 45.0 28.2 31. 3 20.4 34.1 36.6 355 320 490 293 273 43.0 31. 0 4.6 45.8 42.7 27.0 371 41. 9 X 22.7 Emax 440 iimax'kK b 8:2:1 ethanol/methanol/diethylether. a Acetonitrile. Mn(CNPh) 6 [PF 6 ] b Cr(CNiph)/ a Com_2lex "-max'nm 10- 3 . Table 11. Electronic Absorption Spectra of M(CNAr)/ Complexes 11 V *L 7i h*L d1r - d-ir - 7T 7i V V *L *L o-(CNPh) - d11 * d11 - o-(CNiph) - d11 * d1r - Assignment CTI CD GO 3- low energy LMCT bands have been observe d in Fe(CN") 6 and 4- 34 Iv1n(CN) 6 • The two observed peaks in th e o-(C:t'iPh) ..... tg system may be ass i gned to components of 8, vibrational pro gres sion in the symmetrical C===N stretchiJ.1g motiono The excited state value of 1 about Z200 cm·- for this vibration is reasonab le. The spectrum of Cr(CNiph)/ is sirnihr to the Ivfn(II) spectrurn showing aUowed MLC T bands at 36.2kK and 22, 75 kK very close to the ·values for Cr(CNiph) 6 • In addition the LMCT band which occurs at 18. 2 and 20. 4 kK in the :rvm (II) system is observed at 28. 2, 27. 0 kK in the Cr(I) system . This substantial blue shift (8. 6 kK) is b1 line with a net destabilization of the tg level in Cr (I) relative to :Mn(II) making the Cr(I) complex harder to reduce. 12 Electroche mical redox potentials , 35-, 36 are in line with this argument predicting a shift of about 5. 5 kK in the LMCT band. It is of some interest that the MLCT bands in the (d7r) 6 M(CNPh)/ complexes are substantially lower in energy than corresponding peaks in M(CO) 6z analogs (Table 12). The lower energies of d1r -- TT * transitions are probably due in part to the effects of enhanced o- donation in the CNPh complexes , which would tend to increase the electron density on the central metal, thereby raising the energies of both d1T and do-* levels relative to carbonyl analogs. The splitting of 1r*CN(1T v* < 1r h*) by interaction with aromatic ring orbitals must also play an important role, as judged by the high energy of the observed d1T - TT * band u1 M.n(CNMe)/ 8 (43 .1 kK). Preferential stabiliza tion of 1T v * , of course, is not 61 Table 12. Energies of MLCT Transitions in 1\1:(CO)/ and M(CNPh)/ Complexes M drr ...... n* (CO) 1 kKa Cr(O) 35.7 21.8 43.6 25.4 34.6 22.1 42.8 26.5 34.7 22.4 43. 8 27.2 44.5 29.4 49.9 31.1 Mo(O) V/(0) Mn(I) a Acelonitrile solution, 300 K; Ref. 34. b This work. drr - rr* (CNPh) 1 kKb 62 available to a l ky liso cyanide ligands. It follows that stabilization of low- oxidation gr0tmd statf)s of meta.ls through drr back donation to 1Tv* should be much more p ron ounced in aryl- than in alkylisocyanide complexes. Emission Proper ties Introduction ~ The complexes M(CNAr) a whe re J.Vt = Cr, Mo~ V/ and Ar = Ph, DPh, Iph, 4:..clPh were a ll found to show unstructured emission at 77 K in 2-MeTHF glass . The peak positions, width a t half hei ght, and excitation wavelengths are given in Table 13. Complexes of all three metals were also found to luminesce in fluid solutions of pyridine, Xylene, 2 MeTHF, 2 Me pentane, and Me cyclohe.xane. The emission m axima of V✓ (CNPh) 6 and V/(CNiph) 6 at 298 K ·were found to be only slightly solvent dependent (the values are given in T2..ble 14). No emission at 298 K was obse rved from the Cr(I), Cr(Il), Ivfn(I), l'vfa(lI), Mo(I), Mo (II), \V(I), V✓(II) complexes. The emission from the Cr(O) comple xes at room temperature was extremely weak. Information reg~rdjng the r oom temperature emission properties of the complexes in pyridine are reporte d in Table 13 The emiss ion quantum yields for some selected complexes of Mo and Wat 7'7 Kare given in Table 15. The lifetimes of several of the complexes at 77 and 298 K in 2-- :rvTe -pentan e arc given in 450 400 450 380 1 7, 600 (800) 1 7, 600 (1200) 17,200 (2100) 16, 200 (2400) 568 583 568 450 400 618 18, 200 (1400) 17, 300 (2900) 450 400 548 1 7, 900 (1100) 16,900 (1800) 579 559 590 450 17,200 (810) 580 400 17,300 (1150) 578 400 17,800 (1400) 563 450 17,500 (900) 571 w 450 16,200 (3100) 617 450 1 7, 300 (2000) 579 450 16,200 (1600) 619 420 16,300 (2700) 613 Mo 638 VI 420 15, 800 (3000) 683 420 17, 300 (1800) 578 420 16, 600 (1900) 613 420 15, 700 (3200) 298 Kb b Determined in pyridine solution. a All spectra were corrected for phototube and monochromator response; maxima given in nm; energies are given L1 cm- 1 (width at half-height); excitation Vv-avelength in nm. p-PhCl Iph Dph Ph Mo Cr 77 K Table 13. Emission Dataa M(CNAr) 6 Complexes <:,..? m 64 Table 14. Emis sion Maximaa as a Function of Solvent at 298 K a In nm. Tso-octane p-Xylene Pyridine 571 576 581 591 603 65 Table 15. Emission Quantum Yieldsa at 77 K \V(CNPh)c, 0.93 ± 0.07 W(pCNPhCl) 6 0.68 ± 0.08 V✓ (CNDph) 6 0.67 ± 0.10 Mo(CNPh) 6 o. 78 ± 0.08 Mo(pCNPhC1) 6 0.71±0.08 a Excitation wavelength 450 nm, Ru(bipyridine) 3Cl 2 (cf>= 0. 376 ± 0. 037) optical dens ities were matched under the condit ions of the measurements. Table 16. EmissionLifetime Data for Selected M(CNAr) 6 Complexes T Observed a b c ' ' 278 K 77 K < 10 nanosec Cr(Cl\Tiph) 6 Mo(CN1ph) 6 43 ± 2 nanose c 40. 2 ± 0. 5 micros ec \V(CNiph) 6 83 ± 2 nanosec 7. 6 ± 0. 5 microsec < 10 nanosec Cr(CNDph) 6 Mo(CNDph) 6 21 ± 2 nanosec 22. 8 ± 0. 5 microsec a Monitored at 580 nm. b Measured by Steve Milder, California Institute of Technology. c In 2-methylpentane. 66 Table 16 . T:Y1Jical emission spectra at 77 Kare shoW11 for M(CNP h)6 (M = Cr, Mo, \V) in Figures 17, 18, and 19. Discussion ~ , In view of the similarities in the absorption spectra and the gross si.mila:tities of the emission spectra, the luminescence observed in the complexes of all three metals is reasonably assigned to a ligand to m.etal charge transfer. The differences in the emission properties place the Mo and Vv complexes together while the Cr emissions have the more unique characters. The Stoke's shifts observed for the Cr complexes are larger than in the corresponding Mo and W complexes, suggesting that the excited state geometry in the Cr complexes is more distorted relative to the ground state. The emission half-widths for the Cr complexes are about a factor of two broader than the Mo or Vv complexes. The lifetimes of the Cr complexes' emission are much shorter (< 10 msec vs. 50 µ sec at 77 K) than the Mo 8.nd W complexes. The quantum efficiency at 77 K for the Mo and W complexes measured were all quite high while the Cr complexes were estimated to be at least a factor of 10 smaller. Thus in many aspects the emission arising from the Cr complexes is significantly different from that arising; from the Jvio and W complexes. Any model describing the nature of the emitting excited states must be able to account for these differences. 6'7 ,~ I t tt '• , ' , ' .'. ' rI tI ., \ \ I ' r \ t r ' I' r f I , f r ' f f f •' r I f • f f l '\ ''• ' '' ' I J I \ '' \ '',. \ ' \ '\ \ \ r' ., ,.,. ,. '. . ' . ," ... '-'---- ' - - - - - - - - - - ·-.t '-~~·-·----\ nm Figure 17. Absorption spectrum (--) and emission spectrum (---) 0£ Cr(CNPh) 6 al 77 Kin 2-m ethylTHF glass . 68 :'\I I I I I I . ; \ : ' . ' . ' ' ' . I I I I I I I t t I ' • . I t ' t , • I I I \ . ' I \ I I I t I • I • I • I I I ' I ~I • ' I I fi'ffG1 Figure 18. Absorption spectrum (--) and emission spectrum (--- ) of Mo(CNPh) 6 at 77 Kin 2-methylTHF glass. \) l • J I' _._,,, ...'.'.] :t ,~7! · «:~ tt -':J,~0~ n1n e./i\~(F~~ ~ :-u,\w. •~ : •.• ~ ~\• • . ' \ •,· -- l -->--8t:ttt ~-~ - ·~:-. ' ,1 !, ! ' 1 t .. \ ---J - ~7n ~. ;; '<.,y',J/ at 77 K (upper curve) and 298 K (lower curve). I' i ' 'I _, 1 i ! t I ~-I : ~\ ,'' ' ' ~ I ! . , I I 'I ' ii -: I ' l -~~I i ·, I 3 ; a 0 . 4 l t 'c Figure 18. Electronic absorption spectra of Mo(CNDph) 6 in 2-Methylpentane .__:v \,,!,; •:.j,, ~:-?.:.-;·.(?·~ l I! ~ :; ::..~~-~---- ' r~ ,! '< I '•1• 'i ,l ' 'L.. .......1.- •• . .• \ ! P, I :' I ' 'I, l t ' . ! ~ f~ ,. .' l' l '; ' .l \ I , •\ • I 8 ~'\ '\ ' I i~ tJ1 C=.:1 1 fa •1 .~ rtt ~ I '.J ) /• • ; ·, \'\ i!I -~-------:-7 I = '. \ , ~I ,\ ,. l 'lI I ' ~- ! i' • • '1 !,- 'iI r - co C) 70 Characterization of the emitting states in terms of a good working model is also important in describing their photochemical properties. Since excitation spectra are sLrnilar to the absorption spectra in all cases, rapid relaxation to the lowest emitting state(s) is suggested. This suggests that excitations into the bands at A > 300 nm will populate the emitting state(s) ·which are also responsible for the observed photochemistry. Thus by studying the nature of the emh:ti.ng state(s) in these complexes, one most likely is studying the states responsible for the observed phctochen1 is try. The model ,vhich best seems to explain the limited emission . 28 29 . results here 1s the model of Crosby, ' et al. wlnch has been developed to explain the emission spectra of Ru(bipy) 3 2+ complexes. The results are so strikingly similar for the M(CNAr) 6 (M =Cr, Mo, W) and M(bipy) 3 2+ (M = Fe, Ru, Os) that a common model is literally demanded. First, a. short review of the absorption emission properties of M(bipy ) 3 2+ complexes is in order. 6 The absorption spectra of the low spin d complexes of the form M(bipy) 3 2+ where M = Fe, Ru, Os are extremely similar to one another, 37 - 4,3 showing intense (E ~ 10,000 - 20,000) MLCT bands of virtually identical energy and band shape . . The spectrum of 40 .. the Os complex, however, has some additional bands of moderate intensity (E ~ 4000) at lower energy. Spectra are reproduced here from references 37 and 40 (Figure 20). 71 Figure 20. Spectral data for M(bipy) 3 2+ (M = Fe, Ru, Os); (A) from ref. 37; (B) from ref. 40; (C) from ref. 40. A 0 ' - - - -2~5=-------:2::-:o:- - - WAVE NUMBER, c m·1 x 10·3 Figure lG.-Crystal thi ckm·ss, Ul mm; approximately -1 X 10- 3 mole ';o iron. Dotted curves arc analysis of paralle l spectrum only. B <50 1.05 0 0 0 oo 1.OOr 500 5 50 nm cP 'JO) 0 0 0 0 O oO 0.95;=>-=====:;-====c==: (bl 6 ... 4 2 X X ..., 2 .., 24 22 Figure 2. Rela tive quantum yield (a) and absorption spectrum (b) of t ri,(2 ,2'-bipyridine)ruthcnium([I) chloride in an etha nolmethanol gbss (4: 1, v/v) at 77 °K: (a) 3.4 X 10-1 Min a 1.76-cm cell; (b) curve A ~right-hr 1d scale), 1.32 X 10-' M ;n a J.76--c m cell; curve B (left-hand scale), 2.65 X 10-s M in a J. 76-cm cell. Dotted curve is tht: estimated contribution of the si!Jg lct-triplet '.lbsorption. C 0 .J 1.10 w "' ~ >- •- :! 1.00 <( .J ::, w .... a: z 0 .90 <( ::, 0 ., 2 15 (bl 10 X .., 5 Figure 5. Rdativc qt,untum yield (a) and absorption spec tru m (b) of tri s(::>.: '-bi!'yridinc·)osmium\ I I) iodide in an ethanol-meth ano l glass (•l:1, v ;\) at 77'K: (a) 7. 2 X !O-' ;\fin a 1.76-cm ccil, (b) 6.73 X 10-• Mand 1.35 X 10- • t.J in J.7 6-c m cells. 73 The gross emission characteristics of these systems are that no emission is observed for the Fe system while intense emission is observed for the Ru 44 and os 40 systems. In the case of the Os complex, the emission band is found to show good overlap with the low intensity absorption peaks, while the emission spectrum of the Ru complex barely overlaps the higher intensity absorption band. 40 That the Fe complex shows no CT emission is supported by the work of Piper, et al.} 37 who have shown that a weak .9.-.9. band is probably present on the low energy absorption tail of the intense charge transfer transition. The emission lifetimes and quantum yields (at 77 K) are similar for the Ru and Os complexes but show some differences. Both the quantum yield and the lifetime are smaller in the Os compJ.ex (discussions of this are in references 40 and 45). In Table 17 the data available on the emission properties of the isocyanides and the bipyridine complexes are compared. The similarities are striking. The detailed work on the emission spectrum of Ru(bipy) 3 2+ and related complexes has led to the formulation of a weak coupling 28 29 model ' which explains all the experimental results for the Ru complexes. In simple terms the model for rvrLCT transitions couples 5 the d low spin core levels with the excited electron placed in an appropriate ligand orbital. Since the excited electron is localized mostly on the ligands, electron repulsion terms between it and the core electron are much smaller than those found in normal d-d 74 Table 17. Comparison of M(CNAr) 6 (M =Cr, Mo , W) and M(bipy) 3 2+ (:M: = Fe, Ru, Os) Complexes M(CNAr). p 77 K T 77 K T 298 K Cr <0.07 < 10nsec Mo ~o. 7 ~0. 7 40. 2 µsec 43 nsec 7. 6 µsec 83 nsec w 2+ M(bipy) 3 Fe Ru 0 .376 5. 21 µsec 0.6 nsec Os 0.0348 0. 89 µsec 19.211sec 75 1 1 transitions (100 cm- vs.>1000 cm- ). Since the spi.ri orbit coupling i.n Ru is several thousand cm -i, the spin orbit perturbation terms are far more important than the terms a.cisi.ng from the electron repulsion. Thus the emis sion from the lowest excited states of Ru(bipy) 3 2+ has be.en shovm to possess both singlet and triplet- character. Since both types of states can be thermally populated, at appropriate temperatures, the spin allowedness of the emission is a strong fm1ction of temperature. This model, when applied to the isocyanides of Cr(0), Mo(0), V/(O) gi.ves the follmving results consistent with the data. As one goes to the heavier metals, the spin orbit coupling and the crystal field splitting should increase. Thus in the Cr complexes where the spi11 orbit coupling and the crystal field splittings are smaller, the lowest CT excited states will have a small amount of d-d character mixed into them and the energy differences between "singlet" and "triplet" spin orbit states will be sma.11. The emission bands arising from such a "CT singlet with some d-d character" should have: 1) a very short lifetime since it is mainly spin allowed due to the small value of>..; 2) good overlap with the CT "singlet" absorption band; 3) show a fair Stoke's shift and 4) be reasonably broa d. This description fits the emission spectra observed for the Cr con1plexes very well. The heavier metals (Mo and W) where the spin orbit coupling is quite large and the crystal field splitting is also large, should show: 2) lessened .Q-i characte r in the emission band(s) resulting 76 in narrower ern.ission band(s) and a smaller Stoke 1s shift; 2) longer lifetimes reflecting the increasing "forbiddeness 11 of the emission modified to account for the exact thermal population of the spin orbit states popula ted and 3) enhanced absorption due to the spin orbit al.lowed transitions like those seen in the low energy region of 2+ Os(bipy) 3 • (These are observed in the \V spectra, see Figure 19 . ) Since only detailed lifetime and quantum yield measurements as a function of temperature can sort out the exact disposition of states contributing to the emission spectra, further discussion at this time seems unwarranted. It will be interesting to see if the model (which works very well in describing the properties of 2+ Ru(bipy ) 3 ) stands up under close scrutiny for the isocyanide complexes of Cr, Mo, W. Clearly the model should ·work even better for the isocyanide complexes sh1ce the absorption bands a:re much more intense (E = 70,000 vs. 11,000) suggesting that they are much purer MLCT in character than even the MLCT transitions in 2+ J\.1 (bipy) 3- .-- - - One other experimental result of interest is the very small shift in the emission peak in the 77 K vs. 298 K data for the complexes of CN1ph (Table 18). Usually emission maxima determined in a low temperature matrix will be at higher energy than when they are determined in fluid solution since the relaxation of the excited state geometry is not as complete b.1 the "hard" matrix obtained in a glassing solvent. 77 The fact that all the complexes show a reel shift in the absorption spectra at 298 K except complexes of C:t-llph suggests that complexes of this liga.nd are much less subject to exc iied state geometr y changes probably a consequence of the increased steric requirements of the ligand. The solution emission maximum for V✓ (CNPh) 6 and Vl(CN1ph) 6 vary only slightly with solvent (see Table 14 ) suggesting that the emitting state (s) is not perturbed to the extent of forming an exiplex in the better donor solvent. The smaller shifts found in \V(CN1ph) 6 compared to Vl(CNPh) 6 suggest that interaction of the solvent with Vv(CNAr) 6 occurs to a greater extent in the complex of the less hindered ligand. '78 Table 18. Shift in Em ission Maxima from 77 K Measurements in 2- Methy l THF and 298 K Measuren:e nts in Pyridine w CNAr Mo Ph 1600 cm -1 1800 cm Dph 2000 cm- 1 1200 cm Iph 300 cm - 1 0cm pPhCl 1400 cm -1 1400 cm - 1 -1 -1 -1 '79 Photochemistry The photochemical behavior of M(CNAr) 6 complexes (M = Cr(0), Mo(O), \1/(0); Ar = Ph, IPh) has been studied. Two major reaction pathways were discovered: substitution and electron transfer. ~bstitutional Photochemistry The Photochemistry of the Cr(0), Mo(0), and \V(0) Complexes. When M(CNAr) 6 complexes are irradiated in neat pyridine, spectral changes occur which suggest the follmving reaction: hv M(CNAr) 6 + PY - M(CNAr) 5py + CNAr In Figures 21-23, the infrared spectral changes upon irradiating M(CNA.r) 6 are shown.The UV-VIS spectral changes are shown in Figures 24-29 . It is immediately noticed that for complexes of a gi.ven ligand, the spectral changes are very similar for all three metals. The infrared spectra shm:v ii(CN) for the liberated iso1 cyanide occurring at 2115 cm- 1 for Ar= Iph and 2125 c.m- for Ar= Ph. Most easily interpreted is the infrared spectrum shO\:vn in Figure 22whichshows the photolysis ofCr(CNiph) 6 in neatpyridil1e. The two 1 1 bands at 2002 cm ·· and 1960 cm- due to Cr(CN1ph) 6 decrease in i:r1tensity on photolysis while three major bands grow in at 1930, 2030, and 2115 cm- 1• ( The last of which is v(CN) of free CNiph.) From their relative positions and band shapes, it is likely that the 1930 cm - i band is due to an E stretching mode of a M(CN) 5 L C 4 v fragment, 1 involving mainly the four planar CN groups while the 2030 cm- band 80 is one of the two allowed A 1 modes, probably due to the unique CNR ligc1.nd. The other allowed A 1 mode may be weak or obscured by the broad E mode. Spectra of the cor responding carbonyl complexes 46 M(CO)5 L have be en studiect. Althou gh the spectra are similar , they clUfer enough that the ass:i.g1unents presented here should by no mea.ns be taken as conclusive, Further irradiation of tMs 1 Cr(Cl\Tiph) 5py complex shows t he 2030 c m - band decreasing in 1 intensity while the 1930 cm- band rema iJ1s virtually unchanged with (Figure 23) the p eak at 2115 also increas ing in intensity suggestin.g further release of CN1ph with the fo rm8,tion of trans_ Cr(CNiph) 1py 2 which from symmetry considerations should have a sL'l.gle IR active E mode in nea.rly the same position as the E mode of Cr(CNiph):,l}Y, The structural infor:ma.t ion obtained from the IR of the photolysis product of Cr (CNPh) 6 in pyridine is rnuc4 harder to ·i nterpret (Figure 21). Interpretation of this spectrum is complicated by the ' ability of the M--CN linkage to be extremely bent since the ligands'steric requirements do not force linear ity upon the M-CN units as does the CNiph ligand. Uv-vis spectral changes are also consistent with this notion since the spectrum of Cr(CNPh) 5pyconsists of one peak at 410 nm with a long tail eAi:ending out to 600 nm (Figure 24). This m ~ht be clue to gross distortion of the M(CNAr) 5 portion of the molecule since the M(C:N1ph) 5py spectra are "normal" having a low ensrgy peak in each case in the same region where the tail for M(CNPh.) 5py occurs (Figure 27). Similar spectra (uv-vi.s and IR) are obt1.ined in all cases for the Mo and W complexes (Ta bl€ 19). 81 ('. . ).. r'. ,:··::~:' ~\3 ~A ~/ Figure 21. The photoiysis of Cr (CNPh)G i.n neat pyridine (A > 313 nm). Spectra are about 1 min. apart. 82 ---- + - 1:• ,- '";: f': ' <~'.-~,. Fig1ir e 22. --· ._ L1 ,' _ _ _ ___ 1...._ ...,.., .... _ ____ - _______ ...._. - ··· - •:'\ t '} '<::.>' '~:!/ ,..,. ·•; ;• - . \ . .e: < -· • · ~•• ! · -. - ---.1,-..-.~ ·<: . ,........ ,,..,,.,--.,.. .._ .. -· .... I~,; ,.· ,. •• • ., The photolysis of Cr(C:N1ph) 6 in neat pyridine (i\ > 313 nm). Spectra are about 1 min. apart. ~-;._ ~ '<·~;.- .__~:;:.-· t __·-._-;:·:.: r~- ~- ' ; ~:. . •..: i.J' r) !;:;! - ~•.;£. ;...., .:.~;,.-- t : L ~,1 Fig1.1re 23. Continua tion of the photolysis in Figure 22. 84 Figure 24. The photolysis of Cr(CNPh) 6 in neat pyridine by room light. About 10 sec. between spectra. 8G ► l ·. f/;;___ZI \~~tb JI; _ f /} <1--- I} /~~r __,---;::;-,4' c;:·J 'l t·:.·<i if t ~) 11 86 Figure 25. The photlysis of Mo(CNPh) 6 in neat degassed pyridine (A > 313 nm). Spectra are ~ 30 sec. apart. B'l 88 Figure 26. The photolysis of W(CNPh)G in neat~ degassed pyridine (A > 313 nm). Spectra are several minutes apart. 89 < ~lC'- c, (;;5, \:. .. ~-·tJ) / i_([':',.~ ·..r X.:./\.._y ["~ '.~f. l(;) <. .,:, ,_;;,_.. Figure 27. The photolysis of Cr(CNiph) 6 in neat pyridine by room lights. About 10 sec between spectra. 91 ~::-::-;z : (:-;; !~:'Ji , ., ~•, !2::.:.:.':'.j r>":.\ ,., \' :.--:::_~/ ('.-~~ '<:..) 92 Figure 28. The photolysis of Mo(CNiph) 6 Ln neat, degassed pyridine (:x. > 313 nm). About 2 min. between spectra. 7 ·- ';.? ;~.·~~) . 94 Figure 29. The photolysis of \.V(CNiph) 6 in neat, degassed pyridine (A > 313 nm). About 5 min. between spectra. ~c) [irJ <- - ~ ~..,..,,:7.,.... :P'.... ·- - - ~ - - = = = - - - = - - ~ ;, ~ ".,,e::,-, 96 Table 19. Spectral Data for the Photochemi.cal Substitution Reactions of M(CNAr) 6 p(CN) in cm - 1 Complex Cr(CNPh) 5pya 410 (37. 8) Mo(CNPh\py 388 (41. 8 W(CNPh\py · 370 (41. 0) Cr(Cl\Tiph)spy 320 (30.4) 2080,1 940,1730 1930,2030 372 (27. 4) 461 (31. 9) 568 (19. 0) Nia (CNiph) 5PY 405 (44. 7) 530 (30.0) 386 (57. 5) 452 (45. 4) 630 (33. 3) Cr(CNlph) 5 benzb 318 (31. 7) 1925 428 (34. 8) 475 (34.0) 610 (22. 0) Cr(CNPh) 5benz 410 (35. 1) 550 ( 9. 4)sh Mn(pCNPhCH 3 \py + 344(45.1) 410 (15. 3) a py == pyridine. b b enz = b en'.l.yrn1nme ' • . 2075, 2160 wk 9'7 To confirm the fact tha t pyridine was indeed being introduced into the coordination sphere of the metal rather than the formation of a five coordinate species such as M(CNAr) 5 , Cr(CNPh) 6 , and Cr(CN1ph) 6 were irradiated in benzylamine. Spectral changes in these cases are shown in Figures 30-31. Comparison of the spectral data for Cr(CNA.r)sbenz with Cr(CNAr) 5py show similarities since both py and benzylamine are good N donors, but fue peak positions are not in precisely the same place as they would be if a common product M(CNAr) 5 was formed, thus further supporting the formation of M(CNAr) 5 L rather than M(CNAr) 5 • Assignment of the M(CNAr) 5py UV-VIS spectra at this time would be premature, but the large values of the eAi:inction coefficients for the bands suggests that they be conside1~ed LMCT or more likely MLCT bands. Although complexes such as M(CO) 5py have been made 47-49 and the spectra assigned, the analogous lov, energy peaks have been assigned as d-d transitions. Clearly, the high degree of similarity between the M(CNAr) 5 Land M(CO) 5 L spectra suggests that only by a careful study of both systems together can reasonable assic..;:nments be made. Isolation of the M(CNAr) 5py complexes was attempted unsuccessfully. This is probably due to the high boiling nature of the CNAr ligct,nds so that in a solution of lVl(CNAr)51)y in py one could pump off the pyridine but not the CNAr. ~solation of the analogous M(CO) 5py complexes is nrnch easier since the CO released on photolysis can be easily. removed from the reaction. mixture.) After photolysis 98 \ ~-- -.;}7';7~~,=, --1----------;~,- ~-~-: : :·:: ,·: : ·. ~ ' '!. ; _,:~-- '. .' _; · ~~ -~ 1-- : - -:· - --:: -~-- - -~- - ---~-7 -, '.~ ) _; ~·- : - , ·- .~ • . . • , ~-, .,. \~--- -~- - Figure 30. The photolysis of Cr(Cl\Tiph)a in neat benzylamine. Room light photolysis. 99 Figure 31. The photolysis of Cr(CNiph) 6 in neat benzylamine. Room light photolysis. lOO CJ •• .... :1 :, 101 of Cr(C:N1.ph) 6 in pyri dine so as to obtai_n the IR shown in Figure 22 a brovm solid was isolated by pumping of the excess pyridine under vacuum , This brovm solid immediately decomposed on dissolving in undegas sed chloroform. Over a period of months, the brown solid sample (which smelled the unique s :m ell of CNiph) slowly changed to the red Cr(CNiph) 6 accompanied by the distinct odor of pyridine. The Photochemistry of Mn(pCNPhCH 3) 6 ClO4 .,,.__,..,_,~~ The UV-VIS (Figure 32) and IR (Figure 33) spectral changes which occur when Mn(pCNPhCH 3)/ is irradiated in neat pyridine are very similar to those found for the clli'omium complexes. The 1 infrared spectrum shO'NS a band at 2125 cm- correspondin.g to 1 released p-CNPhCH 3 and bands at 2160 and 2075 cm- which are attributable to IVIn(pCNPhCH 3 ) 5py+. The quantum yields for disappearance of Mn(pCNPhCH 3)/ are 0.22 ± 0.01 and 0.21 ± 0.01 at 313 and 366 nm, respectively. These quantum yields are similar to the yield found on irradiating the analogous Cr(CNAr) 6 complexes. 10 2 :--:·-; , • , '- --=---s . [,.:~;~~ ( '"·_~:~ :.._~~ f~:~ ,:; ---::-.. ',·,~·: . _); C' :. ~~ lI .L I 1 ,:..,• ~1 ,:,,,-. 1;_•.~. :r~ ,··;: .·_ ., .. :......~ Figure 32. The photolysis of 11n (pCNPhCH 3) 6ClO4 in neat pyridine (A > 313 nm). J.C3 Figure 33. The photolysis of Mn(pCNPhCH 3 )c;ClO 4 in neat pyridine (;\ > 313 nm). 104 Mechanistic Considerations ✓~~~ .... Of primary b1terest is the large va.riation in the photochemical quantum yield of M(CNAr) 5 py obtained with changes in •both the metal and the aryl group. Appearance quantum yields at 436 and 313 nm are given in Table 20 for M == Cr(O), Mo(O), W(O) and Ar =Ph and Iph. The mechanics of measuring the quanlum yields are discussed in detail in the experimental section, At a given wavelength, the substitution quantum yield shows a large decrease in going to the heavier metals (Cr> Mo> W) and in the heavier metals, the complex of the more hindered ligand has a lower quantum yield. The substitution quantum yield is moderately v1avclength dependent only for Cr(CNPh) 6 , Cr(CN1ph) 6 , and Mo(CNPh) 6 the values being ... about a factor of two larger at 313 nm than at 4:36 nm. The identical values for the quantum yields of Cr(CNPh) 6 and Cr(CNiph) 6 , and their identical wavelength dependences suggest that these two complexes both substitute by the same mecha nism. Since the complex with the hindered ligand has just as high a quantum yield as the unhindered complex, a standard dissociative mechanism is suggested, such as follows: 1) ML 6 2) ML* 6 hv ML 6* ML 5 + L 3) · ML5 L' 4) 1'IL 5 L 5) ML-:, ···· L ML 5 L' (free L in solution) ML 6 - ML 6 (cage recombination) 10 5 Table 20 . Quantum Yields for the Reaction ML 6 PY ML 5py + L in Neat Pyridine 313 nm 366 nm 436 nm Cr(CNPh) 6 0.54±0.01 0.23±0.01 Mo(CNPh) 6 0.11±0.001 0. 055 ± o. 001 'W(CNP h) 6 0. 010 ± 0. 001 0.011 ±0.001 Cr(CNiph) 6 0.55±0.01 0. 23 ± 0. 01 Mo(CN1ph) 6 u. 022 ± o. 01 0. 022 ± 0. 001 W(CN1ph) 6 < 1 xl0- 4 <3xl0- 4 ± 1QQC3/,0 ± 100% Mn(pCNPhCH 3 \ClO4 0. 22 ± 0.01 0.21±0.01 106 step (1) involves excitation of the complex to some reactive excited state either by direct irradiation or by some internal relaxation process from a higher excited state. Step (2) is a purely dissociative process which does not depend on the nature or concentration of the incoming ligand L' (pyridi11e). Step (3) is a rapid step in which the coordinatively unsaturated five coordinate intermediate is trapped by L' producing a product molecule of J\1L 5 L'. Step (4) should also be 6 a fast step but since the concentration of L' is at least 10 times greater than L should be negligible. A few words should be said about step (5), which is the rapid recombination in the solvent cage of the ML 5 species and L. This step could be an important one and tends to decrease the overall quantum yield for the reaction. Since all of the complexes are very similar in electronic properties and the solvent is the same in all cases, this process, if important, should tend to reduce the quantum yield of all the complexes reacting via a dissociative mechanism . . The q1J.antum yields for the W complexes, however, show a rn.arked dependence on the steric requirements of the isocyanide, decreasing by more than a factor of 100 in going from L = CNPh to L = Cl'-Ilph. This behavior suggests that the substitution mechanism for the W complexes shO\vS some associative character. Several mechanisms could be envisioned: 107 ' Scheme 1: Nucleophilic attack on the excited state forming an electronically excited seven coordinate intermediate hv WL* 6 \VL 6 * + L' WLGL'* Scheme 2: Similar to Scheme 1 except the seven coordinate intermediate has no excess electronic energy. hv V✓L 6 * + L' [WL 6 L'] f Scheme 3: Weak nucleophilic attack on the excited state by L', helping L to leave. hv WL 6* WL 5 L' + L The mechanism in Sche me 1 involves the formation of an exiplex with the incoming ligand L 1 • This type of i11termediate with the seventh ligand bound only in the excited state might show up in 50 . . e2>1)enmen . t as a very re d s h'Le ft d em 1.ss1011. • • an em1ss10n Experimentally, if the emission is shifted very much, it would occur in a spectral re gion (\em ~ 700 mn) v1hich is very hard to 108 obse r~.re with a typical phototube . As previously dis cu ssed, the emission maxima of the W complexes are only slightly shifted in nucleophilic solvents (pyridine) from their position in p--xylene . .Although exiplex for mation might be occurrin g., it was not observed spectroscopically. Schemes 2 and 3 are very similar, va,rying only in the life time of the seven coordinate intermedio.te. In Scheme 2, the seven coordinate intermediate is formed by attack of L' on the exc ited state of WL 6 , but the seven coordinate intermediate has lost its excess electronic energy. Thus, it fin ds itself unstable with respect to both WL 0 + L' and WL 5 L' + L but in a shallow potential well. This inter-- mediate would be similar to one which could be envisioned in a thermc1J substitution reaction occurring via attack of L' on a ML 6 6 species . A species of this nature, seven coordi11ate, d seems unlikely to have any sort of minimum in its potential surface since the only empty metal acceptor orbi.tals i.n a ML 6 low spin d 6 molecule are very high jn energy. Scheme 3, which is the most li.kely mechanism, is conceptually analogous to Scheme 2 except there is no minimum along the energy surface. The i.ncomi.ng nucleophile attacks the exc~ted state causing a M--L bond to be broken as the nucleophile forms a bond to the e xcited state of ML 6 • This mechanism e}..rf:rapolates to a dissociative m echanim.n when the bond formation beb.vee n the nucleophile and the electronically excited IvIL 6 molecule does not occur. 109 Electron Transfer Photochemistry Characterization of Products When Iv'i(CNAr) 6 complexes ar·e photolyzed in chloroform, net oxidation of the metal occurs with concomitant formation of CC. The extent of oxidation dep ends on the nature of the aryl group. In Figures 34-36, the spectral changes (UV- VIS and IR) are shown when M(CN1ph) 6 complexes (M =Cr(O), Mo(O), W(O)) arc irradiated. Irradiation of Cr(CN1ph) 6 in CC1 4 produces a yellow solid v;hich analyzes for Cr(CN1ph) 6 Cl and ha s similar spectral properties to all the lVI(CNiph) 6 / HCC1 3 products generated photochemically in solution. The IR data for the M(Cl'-{Iph) 6 products show single v(CN) st-cetches at 2065 cm -1, 1 2050 and 2040 cm- for M =Cr, Mo, and W, respectively. All the data, ii(CN) positions and UV-VIS spectra suggest the common, M(CNiph)/, formulation for these photoproducts (Table 21). Further support of this formulation is the work of Triechel, 12 et al. in which complexes of the form Cr(CNAr) 6 PF 6 have been synthesized from Cr(CNAr) 6 and AgPF 6 . These complexes have been 5 formulated as low sph1 d systems on the basis of their magnetic moments. Si!1ce the crysta l field splitting is usually much larger for the second and third row metal ions tha n for the analogous first row metal, it SP.ems reasonable to also fo rmulate the M(CNiph)/ (M = . 5 - Mo, V/) complexes as low spin cl . The IR spectral data in the v(CN) region for all the M(CNiph)/ complexes are quite similar to the IR spectra of Triechel for th e Cr(CNAr)/ complexes. If M(CNPh) 6 (M == Mo: W) complexes are photolyzed in degassed chloroform, the spectral changes shown 111 Figures 37-38a:re observed. 110 Figure 34. The photolysis of Cr(CNiph) 6 in neat chloroform. Room light photolysis with about 5 sec. bel·ween spectra. 11 1 r 112 Figure 35. The photolysis of V/(CNiph) 6 in degassed chloroform (i\ > 313 nm). About 2 min. between spectra. 11 3 11 4 ·- -- - · · ------.._. - ....... - -- - - ·••"'" ~ 'i ! I '\.7 Figure 36. The photolysis of \V(Cl\Tiph) 6 in undega ssed CH 2Cl 2 (A > 313 nm). 10 sec between spectra. 115 Table 21. Spectral Data for the Oxidation Products of 11I (CNAr) 6 Complexes C_omplex Cr(CNPh)/ _.., UV--VIS nm (E x 10 J ii(CN) in cm 350 (44. 5) 2065,1985 438 (3 4. 0) 21 15,2125 "[Cr(CNPh) 6 Cl] +" [Mo(CNPh) 6 Cl] + 332 (43. 8) 2100,2130 [Mo (CNPh) 6I] BPh4 2100,2125 Mo(CNPh) 6 (P F 6 )2 2135 [W(CNPh) 6 I] BPh 4 2100,2122 Cr(C Niph) 6 + 321 (49. 6) 2065 358 (46. 4) 373 (44. 0) 444 (45.6) Mo(CN1ph)/ 380 (48. 7) 2050 430 (19.5) 465 (48.0) 480 ( 5. 0) W(CN1ph)/ 388 430 sh, wk 470 sh, wk 2040 -1 116 Figure 37. The photolysis of W(CNPh) 6 in degassed chloroform (A> 313 nm). 117 118 Figure 38. The photolysis of Mo(CNPh)c, in degassed chloroform (A> 313 nm). 119 1 New v(CN) stretches grow in at 2130 and 2100 cm- for complexes of both metals, consistent wi.th oxidation of the metal to the divalent state. By adding AgPF 6 to a solution of Mo(GWh) 6 , 51 in acetone the only__product obtained analyzed correctly for Mo(CNPh) 6 (PF 6 ) 2 • This 1 product shows a single ii(CN) band at 2100 cm- . ·when CC is added to a chloroform solution of Mo( CNPh) 6 2+ (Figure 39), an additional 1 v(CN) band is observed at 2130 cm- • The spectrum so obtained is very similar to the photolysis product obtained in chloroform, suggesting they are the same. If 12 is added to a dichloromethane solution of M(CNPh) 6 (M = Mo, VI) and then Na BPh 4 is added, crystals which analyze correctly for [M(CNph) 6I]BPh4 (I'vi = Mo, W) are obtained. IR spectra of solutions of these complexes again show ii(CN) stretches at 2100 1 and 2130 cm- similar to the chloride containing photoproducts. By add111g NaPF6 to a HC1 3 solution of Mo(CNPh) 6 which has been photo1 lyzcd until the peaks at 2100 and 2130 crn- appear, a solid which has the same i:,(CN) region IR as Mo(CNPh) 6 (PF 6) 2 is obtab1ed. The above sequence of experiments is consistent with the existence of cations of the form [M(CNPh) 6 X] + (:M: =Mo, W; x- = I-, CC) which contain the divalent metal with seven lig-ands in the coordination sphere. A variety of Geven coordinate complexes of Mo(II) containing isocyanide and halides are lmmvn. 51 - 55 The seven coordinate W(II) complexes have not previously been reported but the evidence suggests these should be formulated analogously to the Mo(II) compounds. 120 -~ ·, . :v ....... ,, I! I I \\,\ ;;1 \j ·-· ·] :~,\ :?' d ti U .. . - . I l"'t ~) r;,_~::"- ,,; l , . ~,- Figure 39. Curve 1: the ii(CN) IR spectral r e gion of Mo(CNPh) 6 (PF 6) 2 in chlorofor m . Curve2: after addition of Et 4 NC1. 121 The expe:ciments also suggest that the halide ion can be removed from the seven coordinate cation by addition of a suitable halide scavenger, + AgX t • 2+ • generatjng the six coordinate M(CNPh) 6 cations analogous to the • Cr(CNAr) 6 PF 6 compounds isolated by Triechel, et al. 12 Photolysis of Cr(CNPh) 6 in deg;assed chloroform c:tlso leads to net oxidation, but the nature of the product formed is not as clear as in the Mo and W cases. Following the photolysis by IR (Figure 40) shmvs formation of a product which has v(CN) at 2115 c1n - i and a J + 2+ should.er at 2130 cm- . Cr(CNPh) 6 and Cr(CNPh) 6 are reported 1 to have v(CN)'s at 2065 cm-1;1985 and 2161 cm- ,respectively. The shoulder at 2130 cm - i is in the precise position of the ii (CN) stretch of free CNPh, suggesting that this Cr photop:roduct has lost at least one ligand. Most likely is the following thermal reaction which follows the photochemical reactions which generate the Cr(CNPh) 6 2+ cation: Addition of a large excess of CC to a light yellow solution of 2+ Cr(CNPh) 6 (Figure 41) results in formation of a transient brown color (similar to the color of [M(CNPh)~l] + (M = Mo, W)) with immediate bleaching to a colorless solution which shows only the 122 ✓/-:..... \ ., _; , .' c·· .,-- ..:", , ,. f -- ---·-· • . ":\. . ' - ·---- - - - - -- --•·. ,.. . _, ·.,_ ~ ' ,I ( _,~.:-i :: ~' ; ~ :~ ' .. :,•/ . . • ! . ' r... -~--:-: _- _,.1 '-..'. :. _- / \ :· . • \ _·• . -·~/ (' . -~ ~--~ ;:! (~ ·:.\ ~ • ., ··· .,-·.~ · t ,. • . ' • :.. ~. --~~ :,_ ; i~ Figure 40. The photolysis of Cr(CNPh) 6 in degassed chloroform (11. > 313 nm). J.23 --------- - Figure 41. (---) sp Actrum of Cr(CNPh) 6 (PF 6) 2 in chloroform; (--) same sample after addition of Et4 NC1. 124 Ti(CN) of free CNPh. This expe riment is e xplained nicely by postulating uns table seven coordinate i.i'1termediates of the fo r m Cr(CNP h) 6 Cl+ or Cr(CI'.rF q 5 Cl 2 which lose CI'IT'hin a stepwise fashion. J:<.,urther characterization of the solid and chloroform solutions of 'Cr (CNPh) 6 Cl 2 ' by magnetic susceptibility could determine the presence of Cr(C NPh) 6 2+ , Cr(CNPh) 5Cl+ and Cr(CNPh) 6Cr1-, the first two of these beingparamag11etic ,vith two unpaired electrons, while the third should be 0+1 +2 diamagnetic. TheUV-VISspectraofCr(C:t\TPh)'' areshown inFigure42. Quantum Yields ~ " The quantum yields for formation of M(CNiph)/ from M(CNiph) 6 by photolysis at 436 nm in degassed chloroform were found to be 0 .19 ± 0. 01 for M =Cr, Mo; W (se e Table 2_2 ). In airsaturated chloroform, the quantum yield for formation of Cr(CNiph)/ was highly reproducible and consider.ably larger than that obtained under a naerobic conditions ¢ 0 x = 0. 70 ± . 01. The formation of [Mo(CNPh)c,Cl] + and [\V(CNPh) 6Cl] + in degctssed chloroform were cf> = 0.11 ± 0.01 and cp =0.28 ± 0.0 2,respectively, at 436 nm. In degassed chloroform Cr(CNPh) 6 is smoothly converted to a Cr(II) species (see precedLng discussion) v,rhile in m,.-ygenated chloroform, Cr( CI'{P l) 6 + is formed. Mecha.n is tic Considerations ~ ~ ' - , / " \ . / - . . . . . _ _ . - . . . _ , . ~ ~ - - . . . . , . - . . . . . . w.. The be st mechanis ms for the photochemical oxidation reactions of M(CNAr) 6 complexes which one could write should be able to explain the differe nces in the products M(CN1ph)/ vs. 125 '..:.J., ~u,'· -.;,_;J -: ·• ..:. ' ~~~! !":>.~ : ~ . t2 :t • F 1gure '- ... ' . . . ~_./ r,·,·,, ..-·':'-1, ~. . • J <".:~i\ j •• !' . ._., The visible spectra of Cr (CNPh) 6 (-1, Cr (CNPh) 6 P F 6 (---), and CrCNPh) 6(PF 6)2 (· • ·) in CH2Cl2. 126 Table 22. The Quantum Yields for the Reaction of M(CNAr) 6 with Neat Chloroform Compl~x 436 nm Cr(C1'71ph) 6 o. 19 ± o. 01 Mo(CNiph) 6 0,19 ± 0,01 W( CJ\11ph) 6 0.19±0.01 Mo(CNPh) 6 0,11±0.01 W(CNPh) 6 0. 28 ± 0. 02 127 [ M(CNPh\,Cl] +. Two mechanisms are reasonable, both having common in te rmediates for complexes of the hindered and unhindered ligands. Mechanism l: Charge tr an sfer to solvent. hv 1) M(CNAr) 6 + HCC1 3 ..... + £ [M(CNAr) 6 ---HCC1 3 ] + HCC1 2 2a) [M(CNAr)/- - -HCC1 3] M(CNAr)/ + CC 2b) [M(CNAr)/---HCC1 3] - lVI(CNAr) 6 + HCC1 3 if Ar = Iph 3a) M(CN1ph)/ + HCC1 2 tf - [M(CNiph) 6Cl] + 4a) HCC1 2 + HCC12 - C2H2 Cl 4 if Ar =-= Ph 3b) [M(CNPh)/----HCCl3] - [M(CNPh)5Cl]+ + HC-Cl2 4b) HC"Cl 2 + HCC1 3 - CC + C 2 H2 Cl4 2 Mechanism 2: Sn attack of excited state on HCC1 3 hv 1) M(CNAr) 6 M(CNAr)/ lw or b.. 2) M(CNAr) / + HCC1 3 from this step on the two mechanisms a.re identical. Dis cussion Me chanism 1 involves excitation of an electron from the metal to an or bita l mos tly based on a solvent molecule. This inter - mediate can then thermally r eturn to reacta nts or can split out a chloride ion and a HCC12 radical. The follo wing therma l reactions depend on the ste:r ic requirements of the lig,:tnds. If the com.p lex is . unhinde r ed, the H(;Cl 3 radical anion can trans fer a chlor ine radical to the metal via an inner sphere attack on the M(CNPh)/ species . . If the complex is hinde red, the HCC1 3 radical anion cannot oxidize M(CNiph)/ and is destroyed. Mecha nism 2 involves excitation of an elGctron in a MLCT transitio~1. This excited state has a. lon . g enough lifetime to then - reduce a chloroform molecule to HCC1 3 • This HCC1 3 radical anion can then either reduce M(CNAr)/· back to J\,1. (CNAr) 6 or can difuse i11to •the solvent, just as in Mechanism 1. From. this point on, the two mechanisms are identical. An example of I\/lechanis m (1) is the photochemi. ca l oxidation . 56 57 of ferrocene by carbon tetrachlonde : ' hv FeCp 2 + CC11 _, products [FeCp/ ---~l"'] ..... Experimer~bl data suggest that a new absorption band grows into the spectrum of fe rrocene at 307 nr..:1 in chlo:tinated solvents which is not present in ethanol or hydrocarbons. This peak was suggested by 56 Brand and Snedden to be due to a metal to solvent cha.rge transfer band. 129 Mechanism (2) has recently come into vogue with the everexr.::anding amount of work on Ru(bipy) 3 2+ , which in its lowest MLCT state has been shown to transfer a n electron to suitable acceptor molecules .45 , 58 - 63 This electron transfe1· mechanism has also been shown to be facile in the quenching of the emission fromthe lowest excited state. 2+ "4 Recently, work on Ru (bipy) 3 ° and the ferrocene/CC1 4 systems 57 have hinted that in neither case is the mechanism purGly (2) (for Ru) or (1) (for ferrocene). This suggests that I\f[ echanisms (1) and (2) are the two limiting mechanisms, while real syste ms seem to be best described by a mixture of the two, with one dominating. In the case at hand, the absorption spectra of the M(CNAr) 6 complexes in chlorinated solvents show no obvious new absorption bands which could be assigned to metal to solvent charge transfer bands. This suggests but does not prove that Mechanism (2) is the more plausible. Gross similarities between the Ru(bipy ) 3 2+ and the M(CNAr) 6 complexes also suggest that a mechanism similar to that found for excited state electron transfer in Ru(bipy·) 3 2+ is also operative in the M(CNAr) 6 systems. The constant value for the quantum yield for M(CNiph)/ (M = Cr, Mo, W") even though there are large differences in the lifetimes of the lowest emitting states suggest that the actual electron transfer step is very fast, with the quantum yield being determined - by either the diffusion rate of HCC1 3 or its decomposition rate. Emission at room t ernperalure in air-satura.ted chloroform solution 130 was not observed. Emission does occur in other undeox:ygenate solvents, suggesting that the emitting state in each case i..s efficiently quenched by chloroform. The large increase in the quantum yield for formation of Cr(CN1ph)/ found in oxygenated chloroform(0. 70 vs. 0.19)also fits in with a fast electron transfer step followed by another reaction which determir1es the actual quantum yield since 0 2 may be the acceptor. The 0 2 - formed being able to diffuse away before the back reaction can occur. Net oxidation of Cr(CNPlil 6 to Cr(CNPl1)/ has been observed in undegassed isooctane. Although 0 2 has been shown to thermally oxidize Cr(CNAr) 6 complexes to the analogous Cr(CNAr)/ complexes, the thermal reaction with 0 2 was slow enough so that the small amounts of Cr(CNAr)/ formed thermally could be adequately corrected for. Of L1terest is the fact that when Cr(CNP1~ 6 is irradiated in undegassed chloroform (Figure 43), Cr(CNPh)/ is formed while under anaerobic photolysis, Cr (II) products result. This suggests that 0 2 acts as the acceptor when it is present rather than HCC1 3 ; termination of the oxidation at the Cr(I) stage is easily eA'l)lained since 0 2 - is not able to oxidize Cr(CNPh)/ by transferring a chlorine atom in a subsequent oxidation step. The quantum yields for formation of [Mo(CNPh) 6 Cl] + and [W(CNPh) 6 Clr1- are 0.11 ± 0. 01 an.ct 0. 28 ± 0. 02, respectively. difference in these two values- may be a consequence of slightly The 131 Figure 43. The photolysis of Cr(CNPh) 6 in undegassed chloroform (A> 313 nm). 132 {~) C;~:) ,-·;.-__J ·(~ -~: ~~ t_J ., \~_;:: . :i (~:i (\J (;';_) 133 different rate constants for the secondary oxidation of the me taJ center in these complexes. 134 Synthesis Ligand Synthes is ~~~ The method of Ugi, et al. 65 was selected as the most convenient in terms of availability of starting materials and ease of workup. The method gives about a 50--70% yield of product depending on the particular isocyanide. The general procedure is as follows: In a. five liter, three-necked flask equipped with an overhead paddle stirrer and two efficient c.ondensers were placed 500 ml dichloromethane, 1.1 moles of chloroform, 300 ml of saturated NaOH, 1 mole of the appropriate pri.n1ary amine, and approxim.ate.ly 1 gram of the catalyst, benzyltriethylarnmoniumchloride. The resulting two-phase system was stirred vigorously. The exothermic reaction can be monitored by the dichloromethane reflux rate, which is maintained just into the condenser by adjusting the stirrLrig rate. The use of the large flask is somewhat critical in that it allows good heat dissipation without which extremely strong pressure explosions result. The reaction, which makes NaCl in the form of a white precipitate, is usually over in 4 to 12 hours. The layers are then separated and the organic layer is washed with water several times and dri ed over CaSO4 • The dichloromethane is then pulled off under vacuum. The product can be distilled (phenyl, · 2, 6-diisopropylphenyl), recrystallized (2, 6- dim ethyl), or sublimed (4-chlorophenyl). The yield seems to b e least for the 4-chloro substituted compound and best for the 2, 6-diisopropyl phenyl. Characterization was by IR and NMR. 135 Synthes is of Me tal Complexes ., . . ._, ,. .....,...,~~~........,,..._,.....,......,,_.,..._ Cr(CNR) 6 The gene ral method of synthes is used for these compounds 14 was first des cribed by Malatesta, using Cr 2 (C 2 H 3 O2}i • 2I-I 2 O. oG It was observed, however, that better yields were obtained if the reaction ve ss el was heated to 40 °C. The complexes were r ecrystal-J.ized from hot toluene/ethanol in the dark. Crys tals \Vere obt:'lined in all cas es (Table 23). Mo(CNR) 6 These compounds were obtained in about 30% yield as follo,vs: To a stirred slurry of Mo (C H O ) 67 in methanol under 2 2 3 2 4 argon, an excess (10:1) of the appropria te isocyanide was added. The solution irnmed iately turned red-brown a nd was warmed to 40 °C on a hot plate fqr one hour. Upon coolin g, filtration afforded the crude product which was recrystallized from hot toluene/ethanol. The compounds are slightly air sensitive, much more so in room lights. Solutions should be degassed and kept in the dark during recrystallization to avoid decomposition (Ta ble 23). W(CNR)G These compounds were pr epared with difficulty in small yie ]d (5-10 %) by the following method (modification of Ivialatesta and Sacco16 J. A degassed slurry of absolute ethanol (80 ml) and magnesium powder (4g) in a three-necked flask (of at least 300 ml capacity) was prepared and cooled to 0 °C with an ice bath. To this mixture 0. 12 moles of isocyanide was added. 1,rext 8g (~ 0. 02 moles) of V!Cl 6 was added slowly along with 2 drops of acetic acid. Ii.1uch heat is generated. 136 A large number of color changes occur during the reaction. After the reaction ha s proceeded to the point of controlled but sustained ethanol reflux, the ice bath is removed. As the reaction cools down, the product as red crystals is sometimes deposited. This proc edure is rather tricky and at times the yield is zero. Variation of parameters such as temperature, solvent and reagent purification, and scale seemed to have a random effect on the yield. The perfect starting material for this reaction would be W2 (C 2 H 3 O4 ) 4 which has not been made. The product is recrystallized from hot toluene/ethanol., preferably nitrogen, in the dark to minimize losses due to air oxidation (Table 23). [M(CNPh) 6 l ] BPh 4 (M = Mo, W) Complexes of this general form were obtained by adding an excess toluene solution of 12 to M(CNPh) 6 • The resulting precipitate was filtered and dissolved in dichloromethane. Excess solid NaBPh 4 v;as add~d and the resulting slurry was warmed, filtered, and diethylether was added. This crude product was recrystallized several times from dichloromethane/ ether (Table 23). Cr(CNR) 6P F 6 Complexes of this type were obtained as above, substituting KPF 6 for NaBPh 4 • The BPh 4 - salt was also made by this method. These Cr (I) compounds, as well as the compounds containing Cr (CNR) 6 have also been synthesized by the oxidation of Cr(CNR) by AgPF 12 6 (Table 23). 6 2+ 137 Complexes of this type were prepared from MnI 2 by the 17 method of Sacco (Table 23). [Mn(CNR) 0 ] (PF 6) 2 These complexes were obtained by oxidation of Mn(CNR) 6 Cl in glacial acetic acid with an equal volume of concentrated nitric acid. Addition of this solution to a saturated aqueous solution of NaP F 6 gave a red precipitate. The product can be recrystallized from hot ethanol ('J'able 23). 138 Table 23 . Analytical Data for M(CNR)6 Complexes N M 75. 21 calc 4. 51 12 .5 3 7.75 75. 06 found 4. 40 12.52 7.61 70.59 4.23 11. 76 70.89 4.23 11.62 62.92 3.76 10. 48 63.04 3.96 9.98 77.30 6. 487 10.002 76.70 6. 53 9.51 73. 45 6.16 9.5 18 74. 45 6.36 9. 5'l 66 . 80 5. 61 8.662 75.85 5.65 8.58 76.98 8. 745 7 .1 48 79.62 8.58 7. 01 76.81 8. 43 6. 89 76. 84 8.35 7.04 71.649 7.86 6.4 27 71 . 82 7.82 6.35 57 . 49 2.757 9. 578 57. 92 3.04 9. 44 54.752 2. 62 6 9. 122 54. 55 2. 98 9.24 C Cr (CNP h) 6 Mo(C NPh)6 V/ (C NPh) 6 Cr(CNDph)6 Mo(CNDph) 6 W(CNDph)6 Cr (CNip h) 6 Mo(CN1ph) 6 V./(CNiph)6 Cr(pCNPhC l) Nio(pCNPhCl) 6 H 10.865 Cl 139 W(pCNPhC1) 6 Mn(CNPh) 6 Cl Wm (CNP h\,P F 6 [Mo(CNPh) 61] BPh 4 [\V(CNPh) 61] BPh 4 Cr(CNiph) 6 P F 6 Cr(CNPh) 6 Cl 2 Cr(CNPh) 6 BPh4 Mo(CNPh) 6 (P F 6 )2 -C -49.983 H N 2.39'7 8.327 48.15 2.55 7.97 71.14 4.26 69. 61 M Cl 11.85 6.90 5.00 4.36 11. 51 6.90 4.91 52.35 3.13 8.72 5.79 51. 81 3.15 8.63 5.67 68.29 4.34 7.24 68.35 4.52 7.21 63.48 4.04 6.73 63.13 4.12 6.83 70.94 7.79 6.36 70.57 7.78 6.22 75.15 8.25 6.74 75.09 8.26 6.67 80.08 5.10 8.49 79.21 5.26 8.35 52.35 3.13 8.72 5.70 51. 81 3.15 8.63 5.67 140 Experimei}tal Secti.on ~"\Prh-al Measurements ~~~ Infrared Spectra Infrared spectra were recorded on a Perkin-Elmer 225 spectrometer a s Nujol mulls, KBr pellets, or in 0. 1 mm KBr solution cells. Spectra in pyridine and benzylamine were taken in a variable pathlength cell with neat solvent in the reference beam. Degassing of IR solutions was accomplished by bubbling argon through the compound dissolved in a small amount (1 ml) of the solvent. Standard syrin ge techniques were then used to fill the previously dega,ssed cell. Electronic Absorption Spectra Electronic absorption spectra were measured using a Cary 17 spectrophotometer. Room temperature solution spectra were obtained in a 1 cm quartz cell with a quartz insert designed to decrease the pathlength to either 0. 02 or 0. 05 cm. This cell was 68 2calibrated by using CrO4 • Spectra at liquid nitrogen solution were obtained using a low temperature dewar fitted with Suprasil quartz windows and modified to hold a 0. 1 cm cell. Solvents used in general were Spectra grade except for THF, 2-methylTHF, andEt 2 O, 2-methyl pentane, ·which \Vere reagent grade. Low temperature glasses used were EPA, 8: 2: 1 ethanol/methanol/diethylether, 1 :1 isopentane/diethyl ether, 2 methylpentane, and 2 methyl THF. For the ionic compounds solutions \Vere obtained by first dissolving the compound in a few drops of CH 2 Cl 2 and then adding the glas sing solvm t. All solutions were made up in a dark room be cause of .their extrem e sensitivity to 141 light us in g solvent degassed by bubblin g with argon. The solutions were either used immediate ly or froz en at liquid nitro gen temperature where photochemisfry was observed to be slow. A few drops of nitric acid were added to each of the Mn(CN Ar) 6 prevent slow reduction to the Mn(I) complex. 2+ solutions to 142 Emission Spectra ~~-........._,..._ §pectra Emission spectra were obtained using a Perkin-Elmer MPF-3A fluroescence spectrometer. Low temperature measurements were made using an optical dewar. Samples were prepared by dissolving the appropriate compound in the solvent of choice spectrograde pyridine,p-xylene, or 2-methylTHFpreviously degassed by bubbling with argon. These solutions were then placed in Pyrex test tubes and freeze-thaw deg<1ssed on a vacuum line at least four cycles. The tubes were then sealed with a torch and kept at liquid . nitrogen temperature until use. All the above operations were carried out under red light (>.. > 630 nm). Room temperature spectra 3 were measured (on concentrated solutions (10- M)) off the front face of the sample tube. Low temperature spectra were measured by the standard 90 ° to incidence technique. Correction for Phototube and Monochrometer Response All spectra h1 this thesis were corrected for phototube and monochrometer response in the following manner. The intensity vs. wavelength response of a tungsten/halogen lamp was obtained by measuring the potential generated by directing the beam of the lamp through a 0. 5 meter Jarrel-Ash monochrometer light onto a thermopile. Data points were taken every l 0 nanometers from 300 to 800 nm. Then the same lamp was directed into the emission monochrometer and the lamp spectral output curve as a function of wavelength was obtained. Dividing this second curve by 143 the fir s t curve in a point by point manner generates the correction curve. This smooth set of poin h, was then fit to an eleventh order polynomial via computer fit. Corr (A) 2 = a + bx+ Cx .... vrhere a = 4. 63990427 X 10 ~ g = -2. 299848685 X 10- 14 b = 4,. 706047370 X 10 ° C - -- -1. 827965372 X 10 .. 2 i -- - 'l. 061177302 X :lQ- d = 3. 297836079 X 10- 5 j = 1. 955866691 X 10- 22 e = 2. 663711413 X 10 - 8 k = - 2. 2590'72966 X 10·· f = 1.351673912 X 10- 11 h = 2. 963376321 X 10 --17 20 25 1 = 8, 928261361 X 10- 29 By digitalizing the e.xperi1nental emission trace obtained from the instrument and then evaluating the above function at each data poiJ.1t, the corrected spectra were obtained by the use of eq. (1). These spectra were then plotted as desired. eq. (1). Spectrum correct(\) = Corr (A). Spectrum uncorrected (A). Q.uanium yields Lo\v temperature emission quantum yields for the M(CNAr) 6 compounds in 2--methylTHF were obtained as follows : Dilute solutions of the complexes in 2-methylTHF were prepared as described, degassed by freeze-thav.; dcgassh1g (_4 cycles). Next reference solutions of Ru(bipy) 3Cl 2 •.vhich emits in the same general spectral region as the M(CNAr) 6 compounds were made up in EPA. The o . d . of each sa1nplc~ (~ 0 . 2 abs orbance units) was matched at liquid 144 nitrogen temperature a.s closely as possible to a reference solution. Emission spectra were then obtained for both sample and reference under precis ely the same conditions. These spectra were corrected as above, plotted as a function of wavenumber, the area under the two peaks determined, and the ratio between them computed. . equation of Crosby, et al., 69 The was then used to compute cp sample assuming n X = nc. At least three determinations of each compound .:, were made., the average taken as the quantum yield. In Appendices 1 and 2 two computer programs are presented. The first OP TSP EC, written by Jeff Hare and modified by K. M., takes raw emission spectral data which has been converted to digital form , corrects the spectra for monochrometer response, and then plots it in terms of vvavelengih or energy. The second program (AREA KT) computes the area under a curve using the trapezoidal approximation for the area. 145 General P hotoc hemical Measurements and Measurement of Quantum Yields All actinometry was done using Ferrioxatate actinometry .70 - 72 The yield for a 0. 06 M solution at 436 nm was taken as 1.11. Irradiations were carried out in a block thermostatted with a large (~ 30 1) amount of distilled water. The irradiation source was a 450 watt medium pressure Hanovia mercury lamp. The 436, 366, and 313 nm me rcury lines were isolated using 5-74, 7-83, and 7-54 Corning filters, respectively. In addition to the glass filter for the 313 nm line, a 0. 7 cm pathlength solution of 4. 5 g K2 CrO4 and 2. 376 g K2CO 3 in 4. 5 1 of water was 73 used. 3 ml aliquots of actinometer solution were irradiated unc1er the same conditions as the samples. As a check, the quantum yield for aquation of Cr(NH 3 ) 2 (SCN) 4 - was checked at 436 nm against the ferriox,tlate actinometer. Agreement at this wavelength ,vith the 74 literature value was excellent. Substitution Quantum Yields Substitution quantum yields for the following reaction were measured in neat pyridine. hv In every case> a long wavelength absorption band grew in for the ML 5 py species. The appearance quantum yield was measured by measuring the increase in this longwavelength absorption absorption band as a function of irradiation time on a Beckmann D. U. 146 In Table 24 the w8.ve length m.onitore d and the extinction coefficient of that wavelength for each complex are given. These eA'iinction coefficients were meas ured by photolyzing solutions of each comp lex in pyridin e to compl ete conversion. The extin ction co efficients of the product was then obtained from the r a.ti.o of the a.bsorbance of the reactant p<2ak to the absorbance of theprcdu:ct peak assu ming complete conversion. Due to slight photolys is of the product,E'S meas ured in this way ar e a hvays slightly lm.ver than the true value. Repeated m eas urements, howeve r> gave highly reproducible values. The values given in Table 24 are at worst 10% low. Sample P r eparation_ The cmnpounds wero all recrystallized at least twice before use. A small amount of corn.plex (so tha t O.D. at>,. ex>> 2) was pla ced in the mixing chamber of a cell ·which could be degasse d on a vacuum line and then 3 ml of dry, spectrograde pyridine waB pipetted in . This solution was then deg,1.sse d by at least 3 freeze-thaw degassing cycles. All the above operations were carefully carried out in a dark room. Sarnples prepa.red in this manner were then photolyzed. Three independent determinations of each quantum yield were made, with at least 5 data points ta.ken for each run. These values were then averaged. The precision of each quantum yield was very good, varying in somecascs by less than ± 2%. Due to the large extinction coefficients at the monitorin g wa velengths, conversion to prod acts was on the order of 0. 2%, thus avo idin g problems caused by second- ary photolysis and internal filterin g effects. 75 All the qLmntum 147 Table 24. Tlle Extinction Coefficients of ML 5py Used i11 Determinin g the Substitution Quantum Yields for Jv1L 6 + PY - I\1LsPY + L 11.(nm) E Cr(C1'TPh) 6 600 4 , 524 Mo(C:N1?h) 6 570 4,661 W(CNPh)G 590 1, 675 Cr(CNiph) 6 570 19 , 095 Mo(CNiph) 6 570 20,500 W(CNiph)G 580 16, 933 Mn(pCNPhCH 3) 5 ClO4 420 16, 802 148 yields measured were reproducible only under rigorously deoA-ygenated conditions. The products generated are very air sensitive. Oxidation Quantum Yields The quantum yields for the oxidation reaction M(CNiph) 6 + HCC1 3 - M(CNiph)/ + Cl- + organics were measured by following the disappearance of M(CNiph) 6 on the tail of the lowest energ-y absorption. A carefully weighted amount of complex (about 10 mg) was placed into the degassable cell described above. Then exactly 3 ml of carefully freeze-thaw degassed chloroform were distilled into the cell. These operations were carried out in the dark. The disappearance of absorbar1ce was foilowed as a function of irradiation time, usually taking five or six points. Plots of A~- irradiation time were linear out to 15% conversion. The quantum yield was then obtained directly from the slope. These yields were highly reproducible. For M(CNPh) 6 (M = Mo, W), the absorbance was found to increase on the low energy tail so that these quantum yields were .obtained by the same method as for the pyridine substitution reaction, product extinction coefficients again being determi.t'1ed in a separate experiment. The quantum yield data forCr(CNiph) 6 in chloroform need some further discussion. Initial irradiation at 436 nm in chloroform caus es the absorbancc at 571 nm to increase rapidly and then decrease linearly with time. A typical plot of A 571 vs. irradiation 149 time at 436 nm in shown in Fig11re 44. Analysis of the linear decay portion of the data (after 9 minutes) is very reproducible and gives <Pct 1s · app eara:nc e = 0. 19 ± 0. 01. A likely cause of the initial increase in absorbance at 574 nm is photolysis of Cr(CN1ph) 6 to a species of the form Cr(CJ\Jlph.) 5 L where L is an amine impurity in the Cr(CNiph) 6 • Assuming an E of 19,000 for Cr(CNiph)sL, the maximum amount of amine impurity is A == 0. 275, A/E = 5 5 concentratioi-1 >< 10- Iv1 of Cr(CNlph) 5 L -= 1. 45 x 10- M, [Cr(CNiph) 5 L] /Cr(C:N1ph) 6 = 0.44%. ~'""\ i\ l I ! \~i ;,-., ! j ( \ 0 () :\, - 0 (., 0 0 q 0 ,:i. 0 0 ~ . VO\ l ,; -:-- 0 ~.~st\• Ji C> 0 .'11 0 • I _,. ,J 0 0 ✓-7 ~ 0 JO 0 0 3. 246 x 10- 3 solution of Cr(CNiph) 6 in degassed chloroform. Figure 44. The absorbance at 574 nm as a function of time for the photolys is of a ~' . '-1w I i I !, S { I.!, j ! , .,, ;.' ". i' l l h i, :; 'i i 33 I ;/{ r - - - - ~ : - - -- - t 0 c:.TI .... 151 Appendix 1 Modified Version of OPTSPEC (original version written by Jeff Hare) 152 Clli•: i·ICl ll / I) AYl l !_I, / \, V ( 1 0 0 fl i , /\ B ( ! 0 () 0 ~ , [11•; V ( l C, 0 0 \ r B Ml { 1 0 0 0 ) cn:•l lWI //IWT HUJ EIC /, i_[ r isl<, IW/,.1 I\ r IT Cll i·l lill'l/Cili:[>l, il / X T[ :; l' 1 n1iG 'i' H, ~ L ~, r, TH ------ ---· fii.H i: l. X!.T / IW T ):1'1l:/J ! , N'd 1 Lr Ufl ,'L '( t Nl\/, S[ ,.J UHH, J :WMr KL f Nl-[l!,; r D[L Tr 'm() r . --· 1. BC/,LC r I< I~ C 1111 rs H 1[ !HiHi1f'fl or- flIGl'i T:ll:f) Cl\rWS FOi< TH[ 3P[CTRI/M, SCA IS C f<i'-:WlrnA11cr ~lC/. Ll: LW CAIW :; , SC\'/ JS \H,V[Ll2NGHi :, CALE OF CMd) S. C MM lG lHL /~lJ t1 ;'1f; I< L)I' rilGJ.'fYlfD C/dlf)S OF 0/\l;ELJNI.:, C l~ l)AY JS 'i' l·it:: 1; 1.Jf \E f[; fl F S[-U; r1r Didi\., - C. ··-- ··--- ro I';[ r /;II~ Cil''l J' C,,i s HJH .. s llC'. Cf.Fi) I !·JG f>A T /t. r.,E CK · -- PU NC H - St, M[ .. 1 f,- .F Ir. S 'f . C Fl)iJJ~ C11Lil~i!l'.·l rw C/,IH.) l' RC'f:l'[IHtJr; DAT!, liECI~. ro f;[Yfdll 1hE C f>t;:-; [ l,):rlf:, l'Ul~CH f,Uh7 lfJ PJl! f,'f Fntrn C.l)i_UMI\~) nr C!-110 FOL.l.fl\ ! liJ G C D /; T A D C C 1< ; HI I; ~ F C /d; D ::\ MU ;l'f rm T G[ f' R E St:.'. N T If✓ rn !. T I/,l, D A l/\ Cl t: C K • 2 r: nft i1 f., T ( r ~ , I' 7 • I , F ~; • t ) ) 'F' L',rm AT ( (;~X , 7 U' 7 • 1 ; F 7 ; 3 ) } \ - - - - -S - - FDr•: 11,\ ·r ( 2 D ) -· . .. - ----· · ---------------·---·- - ··--- ·----------·-·-- · -- ------- - --·-·------ - READ (S, S ) ~DAT, NEM lT 00 12 U::1 1 ND/\1 REfilH'.,,6) U(M -6 FOl<f1AT(I3) rro1rn.,1c~o) ------ - en .,·n -30 ---- -- - - GL1TO 20 ---- · -- - - - - - - - -- - --------·-- -----·------ ncw(s, nPT Hiln REtD(S,2\ NN,SCA,SCW CA~L DATR[D(N N,HCA,scw,wv,AB,N,NEMIT) Hl{I'f[C6,:'>) (WV(l),AfiO),T:::1,tn ---- - --· - - -- · · - ·- •- •· - • -- ·· - -- - -- - -- -.. IF(NGAS E. EQ.0 ) GO rn JO 20 30 . - - - - - ·-· Rt' AD (Sr<, ) -- I KM- -----YF K l•l O II [ ; () ) r, T -· - - ---· GD 70 lo n QO n n !j 0 READC5,2) HN;scA~scw .. - - - • • -.. • CA l. L fH. 1' I? i: D (Ml-I, SCl, r SC W, R WV ,· SI\ B, M, NE MIT l I·/ I{ IT['. ((,, 3) (f, ~IV ( I ) r fJ /113 (J. 1 , T::: l I I~) ---i O---- -·I F( J Lill'H, GE. 1 ) C/, LL -- l -HII~~ ;f (rJ t KL-, NBADI: r Mr Nt, BS, l✓ P r NTI TL., "D, !', I 'j r 1)EL 1 r- ·-- ZR!Hl, l!ilP L l, L O!F} ----- -- -- !r LlflUM • G[ • 1) C/t.L I, N\IMPL 'f (/, r KN, NE;f,SC, M1 IU,l;~ , DEl.f I RHO, NClPL i, t,P I NDr ... ... ' ZNTITl.,&15,L DJF ) [)/,YA HAS Nfl\'I f3EEtl PLOTlE'.f) - ACCnriDir-!G ro OP1'IliN8 GIVE'N,° . • - -- · · - · - · · ·- - ---·- ·C 12 COli TIMllC - - - -- ----- -GT LW - ---·- l5 ~~ITEC6,i&\ LDIF i& ·--- - FlWll<\T( 2X ,I YlllJ HAVf FXC[rr)[I) TH[ YL1 f\ AL 1~ 2 2 1 H $ z u sc c ____ ___ __,, _ STOP .. · x, n , x rn c c 1 1 , MAXIMUM x .. scAI.C (lf . '30 .. INCHf:S;, 1 ) .... -- -- · . .. ---- - -- ·- -- -· .. .. --- ------ -- - -·-- -- ------- -- -- -- - -- ----·•·-- · -· -· [!H) --- ----- ----SlJ[$IW: !Y HIE· GAT Rf I) ( 1 f)f: , SC Ar SC\, , 7, Yr J, NE llIT ) -------·- -- iH Htf l:l IllU 2'(1000~, Y(IOO()~,IAElZ(l(JOO):IWAVE(lOOO) -- - IDr::,rn ru,:; ____ . .. . . READ(S,lln~~ (l ~AVE (l,,IATT?(I),I~1,1Dn) l I O2 · H'i1 ~~ A TC Cl X , ~ ( 2 !"I ) r 9X ) ) J:q) ' - ----- ---- ·- DO .. 11 ll9 - T::: l, I Qf1 .. _ ____________ _ IF(I~AVE(I\.LE,O) GO 1n 114° J :: ,J t 1 HJ):-:o~o · · · - · - - .. .. - - --·-· -- -------- --- --·-- --··· _______ _____ __ ____ ___ _ __ _.. .. - .. · --.. - - • - -- - · - .. -• · - -- .. 153 ••• • Y(,l):s o.o . Z (.l ) :: i. Lt l /\ 1 ( l ~ ,\ Vf"( I ) ) / f. CI~ • ·- ·- ---- -· Y ( ,J } :: F l, i1 A1 Cl /; iJ ;! ( J ) l / :H~ ,\ --- ----- - ----· ····-· ---- -·----- ---·-------- · ------------ --·---l F (NE MI r ~ N[. O) GG I U2 GU YO 111!9 2 X::Z(J) Xt ::2~ ( nq63.99~0~27+G;7060 ~737 ~X-I.R2796 S3 7%E•02tX*~?+3.297n3Au79E~ zosix ~~ 3 - ?.61,371l ~ 13 f¥ 0G*X*~~+l.3S!G7391 2[~ 11~X*•S - 2,209D~RAn~E-IGA ·· ··· · - - - ·-lX"P- ,, (,+ 2 . <)(, yn r, 3? j I:'·· l '{ -J; X ~ -;,7 ~ 7. 06 J. l 7 73 u2[ ~ 2 O·i, ) '." ~.- (\.!- 1 .. () l'5 ljl,(,/1 69 l r-22~:Y.t,1,Z9-2. 2sq o72 r;G& E-2~ ~ x" ~ l OtR, 92 H26 1361 E-29 a X~ * i 1) ··-···· ··-- · vc,n ~:<11, n.n • --- -·- -·- · - · i-- · ·· · - -- ----- -- -- -i 111<;> cn wn 11ur: • 11 F"f lJI.W Ell[) ---·--- · stm1::0llTrnc --·-- u !·!Pl. T ( t~, Kt; -,Nl3;: M,-t~ A[lS, NP,-Ni I Tl t Nl)pt ·, f)[L r (11H(h tJ[')P; !; Di:r-- -- l) COM HOii/ DI, TB LIU 1·, V ( I. 0 C <l ) , AH ( I OOO') , El WV ( t OOO) , GA £l ( 100 0) Cl1Ml\l'!!J /I WTBLK /SCl.LI: , f--K r NDAT hr lT • -· •• -·• • Cl1 M11 U I l/ I) t l Mr\ I. 1(1 I_ 0 >: ( l Oo (1 ) 1 I, Ml !'l ( !. OOO ) CLll1t101l/Cll Ml'U1/Il[S r, XLUGHI, Yl.tir;n, --- - --· o. 1-1 Eus n t~ RH ( 3 ) , n o <:, ) , r- M, <2 ) I 1,1 l 11, ( 2 5 1, A fl 2: <2 5 r r v oo D.AH G8/IOAlA'r0 0 0 1 1~0/ DATA OD/ 2~0.0 rl.o/ oo) , uf. B H 2 r:; oo; --·-----· • DAYA PMT/f(P6.' 1 l0)I/ -- --· ·- · QAYA IJ' /5/ ITC:~;T::it ------- - YIJIGTl•1 ::-.q O ~ O- - - ·- - --· ·- -·-·- -- - - --·- - - - -------- -- - - -·--·---- CALI. snrn12CHV,N,L,DX~ • ·- -·-----· - DO 109 It:1, N K:::l,DX(I) -· 109 •·· • AAGf;(l )::/,B(K\ • --i 19- · - · ·-· · - · -· ·· - ----·-·--- - -· -· · · -· · -· · -· -·- ·· - · · -- - ·- · · · · - ·-- - - · - ·· · · -- - -·-·· -· -- - - - · · DO 11 9 I::: l , N -A rs c d ~ AA Gs o~ - -· IFCIIB.[Q;o) Gt"I lO 100 ··--·--·-··· ·cALL :in :n12(1J>'IV;M,LDX) [)L) po, I=t ,~; - -- ·- - · -·· -- · ··--·-- ---· •· ··- · -· --·--·---· --· ···· ····· - ·· · - -·· - - -·· · · - -· K:::LDX Cr\ 17~ AA BS (I)=BAH(K\ - - - -·DD-1 89 - 'f.::.\ ,M -·- - ------ - - - 189 DA B(Il=AADS(I~ ·- -- - -··· U l lHll::;:IFXX ( ll•~ V( 1)) -l 1 LBMAX=IFJX(BHY( M)) -- 1. C0 LMJl l:::IF IX(WV(i )){· i ·• · ·· ·-· · ·- - · ···· · ··- - ·-----· ·· · · ·· · ·- ,· ·- -- -- - ---- - · -·- - -· ·- --·· · · · · ·· LM AX= IPIX(HV( NI) - - - --1 F ( l{l. ; [G ~ 1 ) · SC /;Lt= t fl O • 0 - -- -- -- - - - - - - - - - -- - - - - -- - - - --·-·- IF (KL ~r o. 2 j SCALF=So.o · -·-- · ···· · lF(l{l ... EQ •:,) ;,CALE o; 4G,0 - IF(KL.E G.Q ) SCALti?O,O • C· C DAYA HAS BfE':~ :lt'Jl!ffD It/ PIWl'ER 11RDEH FOi) srt.. INE, IIG $CALE HA'.l nn-.· t·l M;srGtff f). IF (tlf> 0 ) -. Gt"! TO . I 07-- -- -- ---------- - - -- -- .co~ IF(L GMIN . GT .LM I N) · ·- -- ···· IF(LG!-! AX; LT ,UIAX) ti MIf/:: r- L tl AT ( L MIN) 107 WMAX=FLnAr(LMAX) AND r~RorEH - PLnnr LMIN=LBHIN LMAX s: Lf3M/,X - · · ·· ·· ·- · ·- -·--·--· -· ·----· -------·-- --• · · ·· · -- ·-····· -· - ·· AKK =~ O.D*( W~AX-~M IN~/~CALE - - - -- --·!< K;; I F l X ( AY- I<) ----- - - - - - - SCC:;~CJ,LC/50;0 t! VL T H ( 1 ) :; ~: M1 N Dll lqq J:;2,KI< . ·: 1·: --- . j ': ~ ' , ~ ; - - •.· . - - ·- • • - • • - . • . :. -:·. · - • ; •• • • • . . ... • r ..:. • • . I : '! ! . • . . .. • - · • .• .. - - - - · .. . . . - ... . · - • I • .. 154 -· · · - · ·· · · I:: J ~ l · - - . . -· -· - · .. .. - -· ... . ... . . I·/ VI, T Ii ( ,1 ~ :-: \•; \'I. r H ( I ) ,i- GCr.: - - 1 L;9 - .-· · COl·ITIIHI[ - -· · · -·- -·-------- ·-·- -- - -- - ---- - --------·--·--- -------- - - ----·- CALI. nurL(N,WV;AR,L~ ·· M::: L . rFrno;.c G~O) Gn TO IOI\ CAL l. IHII' L ( 1-1 r ti;; \' , Fl /; CI LS ~i:c:L -·-- 1 0 I\ --··- C ,\ LI. ·:; P L1: I~/, ( Iv r \>/ V r I- G r I<!< , h \i LT I·! r AB Z) .- - -- - · - -l:F ( II l\. E Q,. (1 ) Gi"I 1Ll l l o ·- --- -- · · · CA LI. SP l.I NA (Mr fJ 1•1 V I IJ Id, r I< t< r ~/ \' Ln1, Bt-, GZ) DO i9 <J r,11 ,K K - - - -·•--·-·-·--- - -· ----- tRZ(I)=A Bl (I)•RABZ(I) 199 - Cl11JTIIHI E 11 0-·- ·--- l F (N Ar➔:; • C Q• o ) ·-- t-t ).- 10 -·10 ! ·· ----·-- - - --·-- - -- Dll 209 J:;J,KK ?.09 C - 101 - -- - ABZ(I)cD[LTiR Hn*ARZCI\ coin rnuE . PLOTTING PtR~~[TERS ARE NnW CALCULATED CALL MAXMiN(AUZ 1 KK,YMAX 1 YMIN) HS C :;;l FIX ( f. CA l C ) ________ -------- - - - - LI.MI I l :: ( I. MI N/ I, :JC ) ~ Nti C LLM/. X:-; ( LMA>: 11,:,C) ·.:.N'.iC ❖ NSC LD!Fg(LLHhX~LLMIN)/NRC . q99 --'-- - - -- - ----- ··--· - ... - - - --- -· - ·--- - -· _.. . - _ . ... iFCl.Dil'.Gl,50) GO TO 102 IF(YHIN,GE.o) GO ro 103 --..Pl1 - .t 39 --I::1, KK ·- -- ---- - - - -- - ABZ(I \=AOZ (1 )•YMIN - 139 ... . COl·JTIIHI[ 103 XlllGTH==1·r~o~1~00IscAl.E -·--- ··· - -· .. LAB;:;:t31 ·--. LLzl,DlF/15+1 - - -- - - n:;;1 ·· --- --- -·-···--··· ·- -- -- ------ -- -- --- ------ --·- -- --·· --- ···--- · -·- --·· - ·-- - - -·- - - - -- - J.J~ 1 - --- -· -- -- -- YMrn~o. ooo . ----- - -- --- · •--- --·--·--- · ---- -- --- --- -· --·----· -------·. YMAx:::z~ooo · - -· - - - -- -• CI\~. L I_/, BC L ( o ~ 0 r- 0 • 0 r Y MIt~ 1 V M/\ X , 1 0 ; 0 r 1 0 ; 1 ABS Ofl 8 AN Cf. I , 1 0 , 1 ) 1)0 !'59 MrlX=! ,LL - -- --- -·-IS 'ff{ T :.L l MI I~ t I 71. NSC .,_ (MOX•• I ) - - - - - - - -- - -- - - - - !ST rJ P:: LL MI N H 7 t- i~ SC* ~m X - -- - -- --- . iFO[!Tf~T .r:o. rsr1W) r,n rn 112 ·· -- -· ·- - --- - --- ·----- -·- ·- · -- •- - -- ··· ·- ·- --- ·· -- - - ----- ·· XMI~=PLn AT(l~TAT) ··-- -- - -·· XH,,X=Fl,nl,T cr:nnP~<lCALE ·- --- -- ---- - - --· --- -- -- -- ------ -- ---- -- ··- ·-·- -·-·- - -· -· XXKA X:;F IJlA T ( }" :n llf') ~ 1; 0 0 /::;C/, LE - - -·- XF-( ISit11'-r GE" ~LL l':,\X ) .-- lfll Dt>=t.LMAX - - -- - -- - lFC ISTl1P ~EO, UY,AXl XMAX:::FUIAl{ISHlP) -· -- ·· SlZE={XM/\ x •• n\T f~)/:,CAL.I: - - ·--· --- ---··· - · ----- ----- ---· - --- -- - · - --····---.• L D Xf ::. I F 1 X ( :; i 7 I:" ) -·-- - ·--·- ·· N!J1•1;~ 0 Sli1f'~l!l1 RT) 1;50/N;,C. - ·- · -- -· -· ---· --- ·------ - ---- - -- · - ----- -- - -- --- ·· · ·· ·- ·- ---· IHI Y::: L+SU* 1 7 t. ( Hl~ X ~ 1 l - -- -·- T. F (MllX. IZ Q; LL) ·-l.l,H ~ 0 - - - - - - - - - - - - - - - - - ,1 AF .. f lriV + Nl/~1 - · - - · --- -- !F (.JAF, GT~ KK ~ Nlt/-\::KK-t-.WV-1- t ·· ··- - ----- -- · --·----- ----- ----- -· ·-·-· --- -- --· --· · -· - lF(liOP.GT ~O) Gi1 Yu 1011 · -•· - 00 1(,9 I"ll,N · ··- --· --· • - - --· ----·-- ·--··•-· -- --- -------- - ·- · --· ·--·-· IP O ! V ( I ) ; GT • ,; VI. l H ( NI I M) ~ Gfl l n 1 0 6 ---·[69 - --- C.ll liTt'lllE-- -----·-- - - - - - - - - - - - - - - - - - - - - - - -l O(, llll=I-1 lI::Y ······· -- ---- ·· CALL Vl,ABEL(O.o,o,o,xMYN,XMAX,nI7E,LDIF, 1 WAVELENGTH {IN NM) 1 ,1n,o, 155 · ·· • ff:,; T , I. f; ) · ·· · · · •• • • • • • • • • • • • •· • • • · •· • · · · · ·· - ·• · · · CA I. I. X Y P l. 1 ( N N r I•: V Cl ,) ; ,·An ( ,) ,! 11 X IH ~I r K XKA X r Y MHi, YM f, X , B f3 1 I, /dJ f t 2 ) - - - ···-•-·· ,! ,i~IJi-l · ····•··· • · ·- ·· ·•••·· ·· -·· ······ ···· •·-·· ·-····-· ··- --····· --·-·· ·•· :·.-··-- ------~-·---· -··--I F Cl. AR~ CQ ;. 1) ~a TQ 104 XF(I,T 0 GT.o) Ct, I. L 1\'.P!..1 •• •• • • •• •• · U , I; U C(, I 7. E , o , OI Y~ T N, YMAXt 1 Q ~ U , 1 11 , ! A13 S I) fl BI, Ii Cl: I r " O , 1 ~ i C AL l CALl SY3E~ n c-t,l) c r,. 1, 1, B c: L ~ D .o , 1 1i 1-1 1,, ~ n c c L D r- , 1 IH, Et. 01 c; n: 1\ r-O , , 1 fl , ·- -- --- ·i'.P MY r lJ 1 ·•·· · • - •· • •·· - -· - • -·--·-· ·· ··- -· ·---· - · -· - ·- ··- ·····- - - - - ----·····-· · ·· · ··-·- ·o u . v c o n , x r n , x , x , r v r n c o ChLL XY l1 Ln1(NU~, WVLT H(liWV),AOZ ( NW V)r XHI N,X XMAX,Y MIN1YMAX,DD,LAB) · · ·· •·· · ·· IF(L/dl ; r:· o : .. l) Gil TO 1'.39 · · · ·· · · •· · ·• · · · •·• · •··• ·· ·· · · ·· .. . . ·· • ·· c Au. LA 13 r: 1. ( fl r z[ , 0 • o , YMrn, YM;, x , 1 o • u , 1 o , , /\ B s n HBt-. 1~ cc , , - 1 o , 1 ~ CAl. L SY~;ENI) ( "' l tl ~ •• • •• • • · · on 10 112 •• /. !ji~ -·--·COIIT I till [ - --·-·---l i2 ll E'i'Uf;ll 102 • F<i.:iurrn 1 mo • ••• • •• ••• • f,\/13l~LfllTXtlE 1W Ml1 L 'r Ui , KL, NB, NA B ~, DfLT r RHO, NOP r l~P, ~lD r IH ITL, ~·, NOl F> CD HM tJ I-l / l) h Tli L K / 1"i V ( 1 0 r, o ) , /, R. ( 1 0 0 0 ) , B I'/ V { l. 0 0 0 ) r H A 13 ( 1 0 0 0 ) - - - - - COMlllm l!W TPL p; ! S C fa.l,F r f, k, ND AT I,,}: T -···- CO1·1110 l·U [' l IM fl U ( / I, L) X ( j OO fl ) i A AH S ( t O O ll ) CO MMCII l/ cm;P t.nn. TEST r XL I/G HI, YU,c; H! OIKENS i il N WVNU R( 2~ 00),AAZ(250Di,BBC3} 1 DD(3~rFMT(2),IDX(2SUOj, 2XH(2':i00), 8/1H7(2'500 ) ·· • · · · ·· ·· ·· · ·· · ·· ·· -· ·· ··· · - ·· ·· ··· ·• · • · •· · DAYA RB/IDATA 1 ,o;o,t.O/ ·--··-·· ·· DA I A ·· DD /2 ,, O; 0 r 1 • 0 I - - - · - - -- - -- - - - - - - - - - - - - - - - DA 'f A FMT/l(F'5.', 1 U 1 / · ···· ·····- ·· · OAYA L.f/'j/ ··· -· • · ·· · · ··· · •· ·· · · ·· · · ··· · · · • ·· ······· ··· ··- ····· · · · ·-··-• ···· • ··········• ·· • · • · · •· · ITEST =l . ••••···• • •• • · YLl~Gl t-1::: 10 ~ O •• ·•••• ••• • ···· ··· ·······•· ····· ··· ······ · ·· ···-··· · ······- ·· ··· •· ··· ······ ·· · ·· · ··· · ···•• ·· DLJ 309 I:::t,N --!i o~- -.riV(l) ~ 1 ,0 0[ · 07/l•I V(I.) CALL snrr12CWVrN,~ox, -- - -- - - - - - - - - - - -·- - - - - ••• • ••••• QO 31.0 X:oil ,N · • K~: t..D X (I) A AB !J ( ): l:: fd)( K ~ DL) ;~ 2 9 I:.: l , I~ ···J 29 -·- AH (I):; I-, ABS ( 1) - - ·· ··· ·- ··- -- -··- ·- - - - - - -- - - Xr- om• [ C. O l C\I HI '.', 0 0 •• · •·· · ··· · · · · DO ~BC) I" 1, H 389 ••··• ·•···•··••• • ······ -·· ······ · ·· ·· ··· ·-······· ···· · ·· · ··· •• •• ••• ••••··• •• Qwvcr,=1;00 E 07/B WV CI) .. CHL. snrn12rn 1·1 V, M,LDX) •··•·• · •• • ·· ··· ·- · ····· · · ·• · · ·• ••••••• •••• •• · ····· ··· - · ·· · · ···· · DL) ~qq I:; ! , Vi ·----- 7•--l<•sLDX ( X ) -·-··--·---·-- - -- - - -- - - - - - - 399 · •· · •·· • ··· • AABS(Il=BARCK) DO 110 9 l :q , M BAB(il=~ AB S(!) · · · · •. · · · · · IHH: I Ik J. F l>'. (f3\', \I ( 1 ) j + I · · • · --• · ·· · • • • -• · · · • • • • • • · · • · • · • • · • - ·• · ·• • •• •• • • · • · - · ·· ··• · · • · · Q09 HBM AX~ IFI X( HW V(M)) - - S00 • --NMJ!s::,JFIX O I V( l' ) ❖ J ----------­ NMAX=IFIX ( WV( N) ) ····· ·· · · ··· IFCKL .CQ. !l SU,L.F :.:2 000 0 0 IF(K~ .E0.2 ~ SCAL[~!u uo.o . . .. . . . . . T. F {K (. • E Q • ?, ) !l CAL["~ 5 o n • 0 IF( Kl..E G.Q~ SC AL[=2rn,o -•· C·---- - DAT A - HA:-_; IJ[ l' N _CH/I Nl~l: D ..1 0 _;~ A'-/[ l·Jll ~'.B ER , - SOHTED- PRClPERI...Y-.f.OR . . Sf>L-l NE.C: ldlD PL 1111 ! NG SCAL f H ,\ ~! fl[f N AS~ I GIH:D • IF(IHJ. EO ~ o ) GC! H1 30/f · • ••· •• -· · · · ··· ·· • · ··· · · · • •••• • · ·•• ·· ··· · · Itt (!JfH-1lll 0 GT.1'~\1i'i) t/Hl N~t<.BMIN ' I , 156 r ! (1/ fHlt, ): , L ·r .. 1; ;.\ f, X ) ,~M AX:::,~,~ MAX II MI f /;: r I_!)/; )' ( 1, !H 1, ) --------·· WMA X::.Ft.n/\ 1 { l~l~A X ) . -------- -- --- ----- ---- -- --- - - - - -- - - -- - - ---------/1 KI<:: 'i () . Of:: ( \'IM/\ >>· i'i HI 14 ) / ~ C Id, P KK::; J Fl X( Id< I< ) &CC::::SCAi. [/'50. 0 ti VI !B IH 1 ) :;, IHj J. 14 VO 3 3 9 ,1 :: 2, I( I{ --· -···--- . - -I·· J .., 1 .--.. -···· - ·--··· -· - ·-- --- -- - - - - · - -~/ Viii?. I< ( ,J ) ;; 1,: \' /·J fJ n: ( Z ) ❖ fl CC - )39 · · COily): !WE C Al. l. Dl! f' L rn , I•/ V , MJ r U Ni::( lF(tHl,EQ , !1) Gl'I 'ID 30'3 - - - - -- CALL-•f1 UPL CM, r, ,, v,. ri AfJ, U - ---·-----·- --·-···-· · - - -- - - - -HcL . ~OS . CA\.L SPLINA(N,hV,AB 1 KK,WVNBR,ABl) ! F Cll ll • C Q ; O ) Gi'I Tl) 3 (l 6 -... - . - . . CALI. pl A ( M, IHi V r f3 A R , I( K I wV Nf:l B A B l ~ . - . . - . . . . . . -- ..-- . .... - . - . ' 00 ll l. 9 I:.: l I KI( ----··---·f,BZCI) :i: ABZ (1) ..dJ,\flZ CIL .. - . ·s rn 4119 CllMTllilll .~06 • IFCNARS~EG~oi Gn 00 429 Ic1, KK r, , T□ 301 . .. .. . Af3Z(nr>f>E:l.TH:Kl1f, ABZO) 1129 'COll'f:i'IHlf - l O1-·-- - CALL· MA 1/. MI I~ ( A f-\ Z , [( K, 'i' MA)( r '(MIN) . • Nsc~rFIX(~CAlE) · ·· •· · •· ·· · tmr,ntk(IHllfUl~SC)fNfiC rm 1·! AX:,; C/,i MAX/ tJ;i r.) *ti[; C ❖ t, [i C · ··- ··· · · liOXf-':,(NtH\flX ••NU MIIJ)/NSC IF(HDIF.GT~SO) GO rn 302 - - - - l F:.... (YMXN~ Gl:·, 0 )-.GO --T0 ·-·3 03 - - - - - - - - - -- - - - - 1)0 3'/9 1:~1,KK ·- · · ·- ·-·-· /IBZ (I\ r;;AOZ ( l ) -..YMII~ st~ Clll/Tftll!E -· - ·· - · -- YIHIJ:ao.oOo · . ... •... ·· · - -·· ·- ••··••· -·· · · · ···-·-· 30~ YMAX=2~000 - ·3 it-- 1_Al3 ::cw I ·· - · · - -- - - - - - - - - - '(M l U'-' O; ooo ·--·--· · ·- XU4GTl1:: 17 ~ o-t. 00/SCAL.E .. - · ·--- -··-· - · . ... .••• ·-- - · - -- ·- - ·· · - - - · - ··-· - · -· - . LL::1WlF/t5 ❖ 1 ·· · lT~:o ··· - - · ·· ·-- ···-···· -· · -· ·-·-·· -- · ·--· ·· ·· ---·- ·--· · · - -· -- ·- -· -- IFCIT.Gr;o \ CALL TJPLT - - - - < - ALL-- ~,nn r I) 2 0 ! Vi~ 81"1 r Kl<, ID X ) - - - - - - - - -- - ·-- · - - · - - - -··-· Dl1 ';,'-;9 p: J t Kl<; Kr:lDX(!) 35~ XR(J)=~~ZCK\ · ·· · · · · · DO 3 (, 9 I ::: 1 , 1, K J&~ ARZ(ll=XR(Jl -·--·-- C/\l.L L A f! Cl ( o • o 10 • 0 r \'H l' I~, YHA X r 10 ~O r-t Oi -LABSORSANCC.J.r .to., .!) _ __ OD 30.9 flrlX:::11U. ··--·- · -· · · LLM~.>::::NNMIN · ···· ····· ·· - · - ··- · -··· ·-- ··- ·--·-· ·· -- ·-· ··- ------- - ·- -· · I9TRTnNNMAX•l7~NSC•CflnX-t) I$ TOP" tllHlA x-1 7 ,:. NS C ,, ~: nx XF ( l RT • i: r, • I fl Y!W ) r, Cl HI } t 0 ---XMIIJ::fLilAl (1STl1l1 ·- - -----·--:_·- ---- · - - - - - - - - -- -···-··- n XMAXcPLnA1(l510P)-SCALE X XI·\ AX= FL n1, r{ 1 '.,TOP l" I ; O(1 /'., CA LE lF(lSTIW;u::.N'l~I N) 1s ·1n 1~:'lN NMIN 157 IF ( ! srnr. I: Q: l~i-.! Ml 1:) ,; i,; ;, ).'. ;·; F UIA l ( ! ~ TLW} SIZE ~ (X MIN • XM~X )/ SCA LE l·/(l J F:-: IF IX ( '. l l i' [) ···-· · · - .. ·· · ··· ···-···· ·· ••..• ... ..•... rm 1-1 == c 1 :, r 1< r., 1 :: ·1 t~ r0 >" 'j 0 It✓:, r: I ii✓ V::: !. -:- :i o q ·: /, ( 1-1 l'I X•·· 1 \ lF(MOx;ro~LL' LAB~O J AF,:: ta:\!{· trn H I F ( ,J I, F • c; T ~ I'. i-( ) I•! ll l•i::: KI< w Ni/ Vv 1 · ·-----·· RMI IJ ::Xi•I ! II / 1 (1 (, O···- ·- -- ··· ·······---- ·-·•···••·- - - R l·I I\ X ::: X MA X It o o • 0 • • • •• • • ••• •• • C AL L V L/d3[ L C(I ,. 0 r O ,. 0 , r. t·I I !✓ RMA >: t n H E I Id) ! F 1 ' [ N( R G'{ • IN • I< I L OI~ /1VE I~ U MB E fl S • • . ll I t 2 'i r 0 , F !·\ T , I. F l C I\ I. L X Y Pl Ii Y ( IW Mf ~I V I✓ r, fl ( t JI~V ) i A B Z (:-! WV ) , X Mrn r XX Mf, )'. , Y t 1! N 1 'l'K A X I D D , L. 1i B ) • • •• • • • • • • • • •• 0 r lF(LAA~[ o~~,~ ~D ro 349 · - ··-····· - - CI\LL· · l A GEi. ( !: l' '/ ff,- (), 0 r \'M I 11 ,~' /•iA >: i i O ~ 0 ; i 0,-1 AB sorrn /-NC(! i '" l or 1·~··-·· ••• CALL SY~[ND(-lrl) • • GO Tfl 310 3119 ·CL11J"!'YIHJE 310 102 REi ll HI J R[Tl!Rll •••·•·•·•• ·· ·· ·· · · · · ··· · ·· · ····· ··· ···· · ···· · - ·· ·· · ·· ···· ···· · ··, · · ·· ······· ···· · · · · ·· 1 ·-··-----·· Clt D · - ········- ··---·-·· - ---··-····-- -Sl/13Rlllll!lff f)lff'' L{ltHH, l·il'i r Atq J) DIMEllSHll·J I·,~/ (l), All (1) · · · · . ... ·· · · . · · · · ··· · ···· ··· . . ... ... .. . . J:: I. t 1509 1 = 21LNTH • . . n~ isoo on -··-·-· ., x::.: 1o • o "ii ~: cr ~ •- ·-- • - - -- · - - - L ~ i r- n: ( x > · ····· ····· - IMt,, r .. 1. • ••••·• ··-···-·· ··· ····· ····· ···--·-· ---· · ··-······· ···· · · ···· · ······· · ······--·· · · ···- ··- ·· ·· · ·-··· •• ·· ··-·· ··· •• • >: X:q O ,. Of. I~IH Hll ) ·-· · · ···· ·· LMJ :::)TIX ( XX ) IF(L;EG.L~ll Gn TO 1501 - - ·-- ~ a Jtl - --· H WC.l ' :: W\>i ( I \ · ·-··· ·····- ·· AA(,! )::AA CJ.~ · · ·• •• •··•· · - · · · · ······ · · · · ··· ···· •····- · -· -·-·-··-··· ······ · · · ··- ··· · - · -··-·· ···· •· ••··· ·· ··-·-········· · ··· · I(= 1 ·- - · ·· · · ·· Gll YO 1'50 0 (!01 AVMl :: FLOAl( K ~ - - · -·-·I<::K 1;- 1--- - · · - -AV:.: F LflA T ( J; ) ·· · ········ ·· WIH,.l):;AVMJ1r W,.' (,l)/,\VHiW (I)/ AV · ···· · ·· -· AA(J)::AVMJ tl\ A(J)/AV+AA(I~/AV . iso0 cn:IrrIw c . .. . . . ..... ... ... . . . . ... · ····· · ··· ·· · · · ·· ·· ····- ··· · ·· - · ·- - ··- - ·- · · · - ··· · ·· · 15 02 Ft1RMAT(3X , ,y nur, DATA I S ACC[PHBLE HIr. SPLTNA' ~ - ·1•50 3 - • Ft1 Rl lA T OX, ., Dllf' l, .. HA~i-Dtl. f iT f) Lr I3, 2>; , .LOA Tf-.• •POINT SJ. /.) - ······ --· M=LIITH~J .... ...... . · l F (M • GT , 0 ) \>! fl IT [ ({, r 1 5 0 3 ) · M • · ···· ·· • · · · · • • · • • - - - • - • - • - • • • · • • • • · · · · • - • • · - • - - • - · • · • · • ·· • · • · · - · • • • • · • ~: fl IT E ( 6 , 1 5 o2 l REHJl~II [tW - - -·- ·S\!3f:011 l! iJf sru NA UiN, X r Yr M,.s ,.r .) -- · - - - --·-· - - - - - - - - - - -- - -C !}PL ti![ nt::vr.:;[f) VE f!'.,Int, Fnfi rir'TSPl:CT 3 DI M[ IJ !l In lJ X ( 1 ) r Y( 1 ) 1 S ( I \ , T ( 1 ) r Id l OOOr 3 \ , B C10 0 0 ) , P ( i OOO) , H ( 1 0 0 0 ) · • • • - • • • •• • • • • • • · 1I::flt i ~ 1 • 7 NM 1 :;fl~•l . .. · -··- · ·· - ··· . ..... ·-· ·· ·- ·. ·- ·· · ·- · ··· -·· · ... •. . . .. ·· · · ·•· ·· -·····--·. ('. . DOS l=l, N - ~ - -.JH U;; x O 1 ! l ()D O 9 x cu - - - - 1'> I::t,N :-\ 1 ACJ,1)cH(I)/ H(I t l) A(l 1 2)=2.0,CH(Itl)+H(I))/H(Itl) I • :· - - , .. 1·· ·, i . • i •. . • •• • .• •. - •.•• 11 . . 12 13 158 AO,:S) q ,o ·· ·•· · · · · .· · · · · . . . . . . ·· ······• · B(I) ~6,0 • C(YCI+2)-Y(i t 1)~/H( I1 l) • CY(Itli " Y(I~)/Hflll/H(Itll · -· ··· f, ( I , !. i •• O • • ·· • •· ·• ·····-- ·-···- ·• •••• •••• ··· · ···- ••••·••• - ·· ··-·-··-·······- ··-··-·--·- ···-·--·--··-· - - - · · · - - - - - · 16 . f,. (11/11 1 '.:• ):::o J.7 . 1 r. Cl, LL Au; COO CIm i r f, r B r P ) () 0 . 3 1) X::. t , 1-1 19 IF(~(I) ~LT. X(I)) GD TO 10 QCl 2 '5 ,) ::: 1 , ,j - - - - - ···· ! f ( 0( I) . L[ 0 X ( ,1 -t 1)) . 2 ~ c: 0 11n ,we · - l O 1·1!U ·1[ U, r 6 l 1 · 21 r.n . ,n _ ;~O ..-·--···- · - 23 b FUi~li/\T(to . CFl:R rm THI: ',T5 1 '11i Fl.1:ll[IH OF Afll~AY f', IS Olli OF ~W :,8/,,G [ l'IIOM BPL INA 1 ~ fl/d ✓ GE on ·, n :1,•5 ····--• 20 .. iT ( ,J . • E O, ·-1) .r,11 ... TO - 30 -··- - - · - - - - · - · - - - - If'' c.1 • u, . ,n r.ti rn ,rn . . T(l) n ( P (,l - t ),',.( X (,H1)•· 8(I)){-.,'d •i + - - - · -·-----··-·· - - - - . . ........ . . .. ..... ····-··· ···-··· · .. . . .... · 26 27 ···--·- ····-··--- - -2 f. .. 29 . .. . ... . .. . - ·· .. ... . . P(J~t( S (IJ-X(J)) tA 3+( 6 ,0fY(J +1)-H(J) ,~ 2 t. P(J)l * (S(l)-X(J))t t ((, ~ O"'- Y( J ) w H l ,l ) H 2 t. P C.l ~ 1 ) ) :~ ( XC.H I ) .., S ( I ) ) ) / ( (, • 0 >\ IH J ) ) . . . .. . . . . . . . . . . . . . co ,-o 3'5 33 _:;o ___ r ( U ;-:-(I' ( J.) i : ( )) (I)->: Cl)) 03 +U i ~ 0,:, Y(J+U !"H C.l.h .t. 2..?. P.( ,1jJ ;1;.(S( n~xuu~ - -- ·-- ---·• +6,0 t. Y(J) ~ (X(Jti1~~(I)j)/(6~0 * H(J)) • • GO TO '.Vi ... .. .... .. .... .. . ·· •-···•- · · · ... . . .... . . . . . . . . 3(, T(I) = (P(JN(\t.(X(J+(inS(l)i~A3t '10 . 46,0iY(J+!\t(S(I)RX(J))~ t(6fO~Y(Jl n H(,l) k ~2 •P (JNl})~(X(Jtl)~scr~,il(6,0RK(J)) _ ._ 35 .: CO ,·ITLIHW-••--·· • • - -- -- - -- -- - -- -- - - ··- -·/IO .. RP.HJr~t! 6"!, - •--•- ··- · f.l ◄ D ·· ------- -··· --·-----··-- -···- ·-·-- -- ·· --··--· - -- ·- -- - -- --- -- ·· ··-- . {)Ii !'.;UBrrnun Nf. /ILG[Gi() rn I A~ fl;\'~ AL 2 · ··· -·· ·· · R1MEll~1 H IU /\(1000,3) 1 11(1000,3) 1 t)(l000r3) 1 B(1),Y(1) ... .. . ·· --·· -· · -· · ·· ··· · ·· -"L -- . .. . _ II. 11(1,2):::A(l,?.) AL ':i -·-·- •ll( 1 r :S '1 ;: />., (1 p?>) - - - -- ·- - -- - - - - - - - - - - -- -- - - ··-"L·- - - 0Y(t) :, f3(1) Al,. 7 •· · ····c-·· ·· PO 10 · ! :-. 2, . N · ··-· · · ·· ·· ·· · · ··· · · · · · ·· ······ · -········· -·· ···-··· · · - -·-· · -· ··- ·· ·····---·--· AL. .8 Il ~ I ., 1 AL 9 · · · · · · · · · · · ,D ( l 1 2 ) :: 1 • · ·.. · · - · · · .. · · · · · .. · . · · · · · · · · .. ·· · .. · · · · ..-- · · · · · .. • -.. -· · -· · -.,· · · ·· · · ·· ·,... · -· · - · · . .... ·· · AL 10 L1 0 , ~ l :: t. (1 r 3 l AL, 11 - ··- - - ·DO, 1. ~. :: · f,( l r I ) .. / - 1101 ,2~ - - -- - -- - - - -- - - -· - -A~ - 12. llCir2' ·~ A(I, 2 ) D(I,1)nJ(I1,3) AL 13 ···--· ·· · lF' (Ml !o(ll{I,2)J<LT.1~f ., 09) Grl i"ll 3'3 ·· ··· ·· · · ·· · · ·- - · · · -···· · ······- ··· - ·-·· · ··-· ·· AL ..... . . 1LJ · 20 CO!HIIHI[: Al. 15 ·-•· 10 YO):. B(U .. nO,t) "- YOl) · · · · -·- · ······ · · · · · ·· - ··- ·· - · -- · ·· · · ·· · · · · ··· ··· · ·-· AL . . . 16 YCII) :.i YUi) / U(l,1,2) AL 17 -·- - - - I - - . 1·1- ·- - - - ------·- -- - -- ·- - ··---·---· - - -A ~- --lf,_ p 2 5 I 1 :, I •· 1 AL 19 . .. YO:!~ ~ (\'(IU "'UCI1,?;) * \'0)) / . lJ01,2J ... .. ··-· · · -·· · -·· ·-···· ······ · · . Al~ 20 l " I ,. 1 AL 21 ..... .. .. Ir(I .E r. ; t ~ r-l1 'fO 15 .. .... . · -· · ·· · ·· ... .... . .. . ·· ·· •· --· ····· •·-·······-· . . AL .... .. 22 en ro 2~ AL ·2l ---· i5 ·-···· HCl"l!RU ··• • --- ·--•-· - - - -· - -- - - ·- - - - -- - - - ·- -- Al.- •24 .. 35 ~rn n !!: u,,1~ hL 2s · · · · -7 · · F ti [1 MA l {/ I 5 X I A rn A . MAl 11 J X 1-: H I C: H RE Q U rn [;'. P I VO T ING OR . I S S l N GUl. AR I . . . .. .. 2 6 1l STllfl AL .. . . . .... .. .. .. . .. END - - - ·- · ·· f.l) f> HOllr r tl f . TI Pl. T- -· ··- ·--··---·-·--· - -011-:Ell'.l l!lil fi CD(2),r➔ C E ,<'~tBCr(Qj,ncGUI) l) A'i' A f\ C: I)/ t C S f r I l Ot / n DATA RCE/1 ?. 1 1 1 27 . .... . ·· -· ···· · · ·-·· ·· · ··· · ···· ······ · · ···· ····· · ·· ··· ·· -•· ... .. . .. . . . AL ······ 28 111/ - - - - - ·- -- ---- AL ·- - ~9 - 159 • • DI, 1 A n CF / t ( nL I ' 1 I V T NF I , I ·P H A I 1 1 ~ [ ) t / DA r A nc G1 , 1. , Ill~ , , IT ;,?. ;;I , ' , , '. 1,. N , 1 ·- - •• ·-- ·- ·- - C Id, I. S YS~;~' t•i ( P ~ 0 r 9 • O 1 0 • 5 i nCD ,. (, -, 0 i O ) ••• CALL SYSSY~(i?,n,~.rs , o.~,RCE , 7, o ~o ) CA LL SYSS YM(l2;0 , o. o, o,25,A CF , t 5,o.o ) CAL L SYS~YM (l 2;o , 7.5 , 0,25,~CG , l 5,o;o ) HE YUl~ll EUO :' --··/ / DATA··-·- · D!'J - - 1c----·- - - • 160 Appendix 2 AREAKT 161 D 1 I\ i:. I/ :n ll!~ :· ffd} Z { ,'::i Oo) r 1,: AV U SOO) r AO (( •:; 0 \1) , Y.r//, VE (.StO o.) r 1-; t-i lJ MC !i,O _G )i ! FOIUl/, T(I3) 10 F nr111 -'1. i' Cl 5 , 2 rt O; ') \ ·m:AD(:;, 1) IJSU · ·• ·• · ' •. ·· · · · ·· Pl)? .;:,t,NfJC-!' -···- -- --- R[/,D ( 13, ! 0) lOR, SC A 1 !.C 1•1--- ··-·- ·- - ·-··-··--·-·---- :: J · · · ·· · ·· i .,•,;,, - - -·-·-· l I)!~:~ I [) !~ I •; .J READCS,3) (IWAVf(!l,JAAlCl),I=t,IDR) . FORH ~T CClX,5{217jrQ X)) • K::o Dn /( I :, l, pm .ff(IH/. V1.; o \ ;1_r. ~ o~ _c; nrn-. 4 - - - -- -- - - · · - - - - - - - - -- -- - K~Kt ! AHZ u:) ::ABS (FUI AT CJ; Ml 7. (T)) l '2-C f, ) HAV[(Kl=rLnAT(l~hVf(Ii)/SC~ t/lHJIIC !'.l :: t:o Eo1n:A\'E' (l'. l X"'~/AV[(I() _ _ _ ___ )'. 1 :;2 ;'; ( _,/1 Ii 3, 993 01127-i·lj ~ 7 0 60 ~ 7:~ 7 ;\ X-, 1 • f-:27'165:.H;![!"02 i ,):'. >1;1'2t-~ ,i 297 ll 3 6 079 [,.,_ _ Z05tX ~R3• 2.60 37 1l ~ i3 E,,OR* X*~Qtl;3S16'l3 9 12[ - ll*X• *5-2,299iqB6R~ E-14A ZXiA0 t2,9 63 3 76 3? 1E • l7A XA* 7•7.U 6 1L77302[ q2QAXtA Atl;9S58h66 9 ICN22AX** Z9-2.25Q0 72Q66Eu2~~XA~ lO+A,92026!36tE~29~X*All) • - AHZ(l( ~:-;X \ >'<AEZ (K) .. -- ---·· --· l(SAVl::cl~ .. 1 -· -· ./1 - --- COIH! llll E - - - A-::. 0 • 0 - · --·· · - DO ') I J :. 1 , K:~AV I: 6 FORHAT(lX, P lO.Z,!10~ - ,5 -- . . A::A,, ((A l3 2(IJ ... )+Afl7,(IJ - ... +t)}*( W!,Jl)M(IJ .. . wHI Tr: ((, I (:, ) A, ,l - -~ 2- - COIH l:llll[- - - - · STllP - - ·-· · ·· - EIW · //DATA DD ~-rl~Nl/MCIJ . . +U)/2.0) . 162 References 1. L. Ma lates ta and F. Bonati, 11 Isonitrile Com plexe s of Metals," ·w iley, New York, 1969 . 2. I. Ugi, ed . , "Isonitrile Chemis try," Academic Pres s, New York, 1971. 3 . P. M. Treichel, Adv. OrganometalChem . , !l, 21 (1973). 4. F. Bona ti and G. Minghetti, Inor g. Chim . Acta, 9, ,..._ 95 (1974:). 5. P. Fantucci, L. Naldini, F. Cariati, V. Valenti, and C. Brusseto, J . Or g8,nom etal Chem., §±_, 109 (1974). 6. A. C. Sa rapu and R. F. Fens ke, Inorg. Chem., U, 3021 (1972); 14, ,,...,,.._ 247 (1975). 7. Y. Dartiguenave, M. Dartiguencwe, and H. B. Gray, Bull. Soc. Chim . France, 4225 (1969). 8. P. C. Fantucci, V. Valenti, and F. Cariati, Inorg. Chim. Acta, J, 425 (1971). 9. J. M. Pratt an d P. R. Silverman, J. Chem. Soc. (A), 1286 (1967). 10. V. Valenti, A. Sga mellotti, F. Cariati, andL. Naldini, Ric. Sci. , ~!:., 1230 (1968). 11. A. Sa cco and F. A . Cotton, J. Amer. Chem. Soc., 84, 2043 ~ (1962). 12. P. M. Treichel and G. J. Essenmacher, Inorg. Chem., ~' 146 (1976). 13. G. Gondroelli, L . Giallon go , A. Giuffrida, and G. Romeo, Jnoq{, Chim. Acta, 7_, 7 (1973). 163 14. L. Malatesta, A. Sacco, and S. Ghielmi, Gazz. Chim. Ital., 82, 516 (1952). -"'"' 15. K. R. Mann, M. Cimolino, G. L. Geoffroy, G. S. Hammond, A. A. Orio, G. Albertini, and H. B. Gray, Inorg. Chim. Acta, 16, .,._,.._ 97 (1976) . 16. L. Malatesta and A. Sacco, Ann. Chim. (Italy), ~' 622 (1953). 17. A. Sacco and L. Naldini, Gazz. Chim. Ital., 207 (1955). - 86, .,.....,.,._ 18. P. GarisandS. M. E. Haque, Chem. Ind., 978 (1972). 19. Computer programs available through the CRYM crystallo- graphic computing system on the IBM 370/158 computer at the California Institute of Technology. Scattering factors for Cr, C, and N were calculated by the method of D. T. Cromer and J. B. Mann, Acta Cryst., ~ ' 321 (1968). The scattering factor for H is that given in R. F. Stewart, E. R. Davidson, and W. T. Simpson, J . Chem. Phys., 43, .,.....,.,._ 3175 (1965) . 20. (a) G. Germain, P. Main, and M. M. Woolfson, Acta Cryst., Sect. A, ~' 368 (1972); (b) P. Main, M. M. Woolfson, L. Lessinger, G. Germain, and J. P. Delclercq, "Multan 74, A System of Computer Programes for the Automatic Solution of Crystal Structures from X-ray Diffraction Data," University of York, York, England and Laboratoire de Chemie Physique et de CristaHog1·aphie, Louvain-la-Neuve, Belgium, December 1974. 1'64 21. Least squ8.res refin ement was accomplished by the program UCIGLS which is derived from ORFLS, with substantial modifications and additions made at BrooldiaveD, Wisconsin, and Northwestern. The present UCI version is written in Fortran IV. See R. J. Doedens and L. F. Dahl, J. A_p1er. Chem. Soc., .,....,..._ 88, 4847(1966) . 22. L. 0. Brockway, R. V. G. Ewens, and M. W. Lister, Trans. Faraday Soc., ~' 1350 (1938). 23. D. S. Matteson and R. A. Bailey, J. Amer. Chem. Soc., .,....,..._ 90, 3761 (1968). 24. W. D. HorrocJr,._,s, Jr., and R. Craig Taylor, Inorg. Chem., -"-2, 723 (1963). 25. I. Ugi and R. Meyer, Chem. Ber., -"--"93, 239 (1960). 26. N. A. Beach and EL B. Gray, J. Amer. Chem Soc., .,....,..._ 90, 5713 (1968). 27. This complex was made by the method of D. S. Matteson and R. A. Bailey, J. Amer. Chem. Soc., .,....,..._ 90, 376 (1968). The small amount of complex obtained was characterized by IR and used immediately, since it is quite unstable. Its UV-\71S spectrum is very similar to Cr(CNPh) 6 wi.th bands occurring at 300 nm (sh), 370 nm, and 440 nm (sh). 28. n. VI. Harrig,mandG. A. Crosby, J. Chem. Phys., .,....,..._ 59, 3468 (1973). 29. IC VJ. Hipps :1nd G. A. Crosby, t.T. Amer. Chem. Soc., -"--"97, . 7042 (1975). 165 30. R. G. Pearson, J. Ame r . Chem. Soc., 91, 4947 (1969). ~ 31. M. D. Sturge, Solid State Pbvs., JQ, 91 (1967). 32. J. W. Dawson, T. J. McLenan, V,f. Robinson, A. Merle, M. Dargiguenave, Y. Dartiguenave, and H. B. Gray, J. Amer. Chem. Soc.,~' 4428 (1974). 33. J. V✓. Dawson, H. B. Gray, J. E. Hix, J. R. Preer, and L. M. Venanzi, J. Amer. Chem. Soc., .,.__,,.__ 94, 2979 (1972) . 34. J. A. Alexander and H. B. Gray, J. Amer. Chem.. Soc., 90, ,r-..,..._ 4260 (19 68). 35. M. K. Lloyd and J. A. McCleverty, J. Orgmet. Chem. , .,.__,,.__ 61, 261 (1973). 36. P. M. Triechel and G. E. Dine en, J. Orgmet. Chem., ~' C20 (1972). 37. R. A. Palmer and T. S. Piper, Inorg. Chem.,~' 864 (1966). 38. C . K. Jorgensen, Acta Chem. Scand., .,.__,..._ 11, 166 (1957) . 39. F. E. Lytle and D. M . Hercules, J. Amer. Chem. Soc.,~' 253 (1969). 40. J. N. Demas and G. A. Crosby, J. Amer. Chem. Soc., 93, .r,.r--. 2 841 (19 71) . 41. G. A. Crosby, V✓. G. Perkins, and D. M. Klassen, J. Chem. Phys., 43, 1498 (1965). -- /'./',. 42. D. M. Klassen and G. A. Crosby, J. Chem. Phys., 48, .,.__,..._ 1853 (1968 . 43. R. W. Harrigan, G. D. Hager, and G. A. Crosby, Chem. Phys. Lett:_; ~' 487 (1973). 166 44. J.P. Paris and W. Vl. Brandt, J. Amer. Chem. Soc., -"-" 81, 5001 (1959). 45. C. LinandN. Sulin, J. Phys. Chem., -"-" 80, 97(1976). 46. C. S. Kraihauzeland F. A. Cotton, Inorg. Chem . , J, 533 (1963). 47. M. Vvrighton, Inorg. Chem., 13, 905 (1974) . .r-.r,. 48. M. Wrighton, G. S. Hammond, and H. B. Gray, J. Amer. Chem. Soc., ~' 4336 (1971); Mol. Photochem., ~' 179 (1973)--: 49. M. Wrighton, Chem. Rev., 74, 401 (1974) . .r-.r,. 50. L. S. Forster, "Concepts of Inorganic Photochemistry," A. W. Adamson and P. D. Fleischauer, eds., V/iley-Interscience, p 31. 51. Personal communication from Steve iv1ilder. 52, D. L. Lewis and S. J. Lippard, J. Amer. Chem. Soc., .rv-, 97, 2697 (1975). 53. M. Novotny and S. J. Lippard, J. Chem. Com.m., 54. J, 02 (1973). F. Bonati and G. Minghetti, Inorg. Chem., .,..._ 9, 2642 (1970) . 55. D. F. Lewis and S. J. Lippard, Inorg. Chem., 12:, 621 (1972). 56. J. C. D. Brand and VI. Sneddon, Trans. Farada.y Soc., 53, ~ 894 (1957). 57. 0. Traverso, M. A. Scandola, F. Scandola, Attidel II Convegno Nazionale di Chimica Inorganica, Bressanone, July 1969, p 15'7. 58. C. R. Bock, T. J. Meyer, and D. G. Whitten, J. Amer. Chem. Soc., ~' 4'710 (1974). 167 59. G. Navan and N. Sutin, Inorg. Chem., .,.._,, 13, 2159 (1974) . 60. G. S. Laurence and U. Balzani, Inorg. Chem,, ,,.,..,__ 13, 2976 (1974). 61. C. R. Bock, T. J. Meyer, and D. G. Whitten, J. Amer. Chem. - Soc., .r-..r-. 97, 2909 (1975). 62. C. T. Lin and N. Sutin, J. Amer. Chem. Soc., 97, 3543 (1975). -'"'-'"'- 63. C. CreutzandN. Suti:n, Inorg. Chem., ,,.,..,__ 15,496 (1976). 64. J. Van Houten, R. J. ·watts, J. Amer. Chem. Soc., ,,.,..,__ 97, 3843 (1976). • 65. W. P. V✓eber, G. W. Gokel, and I. K. Ugi, Angew. Chem. Internat. Edit., 11, .,.._,_ 530 (1972) . 66. W. L. Jolly, "The Synthesis and Characterization of Inorganic Compounds," Prentice-Hall, Englewood Cliffs, New Jersey, 1970. 67. A. B. BrignoleandF. A. Cotton, Inorg. Syn., ,,.,..,__ 13, 87(1972). 68. G. W. Haupt, J. Optical Soc. of America, 42, .,.._,_ 441 (1952) . 69. J. N. Demas and G. A. Crosby, .,.._,_ 92, 7262 (1970) . 70. C. A. Parker, Proc. Roy. Soc. (London), ~ ' 104 (1953). 71. G. G. HalchardandC. A. Parker, ibid., A235, 518 (1956). ·~ 72. J. G. Calvert and J·. N. Pitts,"Photochemistry," John Wiley and Sons, Inc., New York, 1966, pp 783- 786. 73. G. Geoffroy, private communication. 74. E. E. \1/egner and A. V-l. Adamson, J. Amer. Chem. Soc., .,.._,_ 88, 394, (1966). 75. O. Kling, E. Nikolaiski, and IL L. S. Schlafer, Ber. Bunsenges. Physik. Chem., ~£~ 883. 168 CHAPTER 2 SPECTRAL CHARACTERIZATION OF Rh(I) ISOCYANIDE COMPLEXES 169 There has been considerable recent interest in the optical spectra and electrical conductivities of platinum compounds in which direct metal-metal interactions are present. l - 5 Perhaps the best lmmv1.1 examples are the double salts, such as [ Pt(NH 3) 4 ] -[ PtC14 ] (Magnus' green salt or MGS). 1 Low solubility of the double salts has generally restricted study to solid samples, although it should be noted that Isci and Mason have obtained electronic spectra for . certain [ Pt(CNR) 4] [ Pt(CN) 4] complexes in ethanol solution. 6 Many simple platinum salts also possess unusual properties ~' 3 The planar ions in these compounds, as in IvIGS, stack face-to-face in infinite columns. Ho-wever, with the exception of one or two mixed-valence aggregates, notably [ Pt(C 2 0 4 ) 2 ] 11 l,6n- , complete dissociation to monomeric fragm ents occurs in so lutim . Even the copper-colored, mixed-valence Krogmann 's salt, K2Pt(CN) 4 Cla. 3 " 3H 2 0, forms a nearly colorless solution containing discrete Pt(II) and Pt(IV) comp iex ions. 2 8 We have begun a syst ematic investigation of metal (d )s metal (~ ) interactions in solution. Systems that appear to be highly 7 promising a re based on planar Rh(I) and Ir(I) ary lisocyanides. Here ,ve report an electronic spectroscopic characterization of the oligomers formed L11 solutions of Rh(I) isocyanide complexes. Experimen hl The starting material [ Rh(COD)Cl] 2 was prepared by the 8 method of Chatt. The isocyari ides were prepared via the Hoffmann 9 Carbylarn.ine reaction and were pur ified by vacuum distillation. 170 Table 1. Analytical Data H N calc 55.8 3.30 9.30 17.1 found 55.67 3,84 9.32 16.84 calc 74.85 4.80 6.72 found 74.59 4.82 6.76 calc 50.92 3.03 8. 49 15.59 foun d 50.66 3.22 8.39 14.58 calc 36.65 5.38 10.69 found 36.3 6 5.22 10.63 calc 68.79 6.93 8.02 found 68.51 6,97 7.97 Rh(CNcyclohe xy l) 4 BF4 calc 53.69 7.08 8.94 found 53.53 7.00 9.00 Rh(CNcyclohexyl ) 4 P F 6 * calc 49.13 6.48 8.18 found 43 . 84 5.75 7.16 calc 53.65 3.94 7.82 14.36 2160 CH 2 Cl 2 found 53.79 3.80 8.03 14.06 Rh(C NPh)4 BF 4 Rh(CNPh) 4 BPh4 Rh(CNPh) 4 PF 6 Rh(CNi-propy l) 4 P F 6 Rh(CNi-propyl) 4 BP h 4 Rh(CNPhCH 3 ) 4 P F 6 Rh -l C ii(CN) cm 2160 CH 2Cl 2 2160 CH 2 Cl 2 2160 CH 2Cl 2 2160 Nujol 2160 Nujol 2160 Nujol 2160 Nujol Cl Rh(CNt-butyl) 4 Cl Rh(p-CNPhCl) 1 BF 4 calc 51.01 7.71 11.90 7.53 found 50.94 7.85 11. 64 7.36 calc 45.45 2.18 7.57 found 45.46 2.19 8. 10 * Contaminated with E:P F • 6 2160 CH 2 Cl 2 2165 Nujol 171 recrysta lization and spectral measurements. Synthesis Rh(CNR) 4 Cl. lO' 11 An excess of the des ir ed isocyan ide was added slowly to a warm benzene solution of [ Rh(COD)Cl] 2 • The immediate precipitate was filtered, washed with cold benzene, ether and air dried. Complexes of phenyl, cyclohexyl, isopropyl, tertbutyl, p- 'methoxyphenyl, and p-chlorophenyl isocyan ide were synthesized by this method. Rh(CNR) 4 BF 4 • Crude Rh(CNR) 4 Cl obtained above was dissolved in the minimum amount of water, filtered and the resulting solution was then added to a saturated water solution of NaBF4 • The resulting precipitate w2-s then recrystallized from acetonitrile. Similar methods were used to synthesize BPh4 - and PF 6 - salts using NaBPh.,_ and KP F 6 , respectively. Spectral Data Absorption spectra were measured using a Cary 17 spectrophotometer. Spectra were obtajned in 1. 00, 0 .1, and O. 006 cm cells , 12 all of ·which were calibrated with K2CrO4 solutions. Infrared spe ctra were m e8,sured u slng a Perkin-Elmer 257 infrared spectrometer. Emission and excit--1..tion sp ectra were obtained using a Perkin-Elmer JVTPF-3A fluorescence spectrometer equipped with a standard accessory which corrects excihtion spectra for varying lamp intensity ,md monochromator efficiency from 200-600 nm and corrects emission spectra for varying photomultipli2r tube re sponse and monochromator 172 efficiency from 400 - 700 nm. The spectra reported here are corrected. Measurements at 77 K were performed using a specially constructed low tempera ture quartz dewar. The absorption spectra for Rh(CNPh) 4PF 6 in 0.1 lW 'I'BA+PFi acetonitrile at 25 °C and Rh(CNt-butyl) 4 Cl in 0.1 M NaCl/water at 25 °C were obtained as a function of monomer concentration, C O • The collected data at selected wa velengths are given L'l. Tables 2 and 3. A 3 was taken at 750 nm rather than at the p eak position, 727 nm, to avoid overlap ,vith the tail of the 568 nm absorption . Table 2, .Absorption Spectra as a Function of Concentration for Rh(CNPh) 4 P F 6 in O. 1 M TBAP F 6 c in moles /liter c~o A 1 (568 nm) OoO Co 000:35 5e9 0~00130777 C.239CCO 0.5 3 1:0C 0.001 4 13 5 S 0~~26400 L l c CCCO l .. czc-;c;g L6cl, CJS9 202c; s sc;q 0 • 0 0 2 0 3 t,6 7 0 .. 002 !+i.J4S l 0,002 539 78 A 3 (750 nm) 0 ,. 0 o.o 0., 0 ·- ------·-- ·- 0,,0 o .. 0 Ooo · o .. o 0 ., 0 o.,o - ----- ---- 0~003 10502 2.L.59C:S9 c .. 00392L:,: uo · C,OQL,362 73 4.<'dC0CC O~OC444007 C.0 0~1 1 9 10 4~5 8 0000 8,,cc c; c;q<; 0.,J07lii '7 57 S.94.0CCC o., 9 1, 000 0 OeOU :J .'..>:::i0 2 0 C u J :J :2 o '.) O!t O.,Ol 2S61JO 12 ~S6SS S9 1~4 80000 1. 780000 C.012 66858 24.c1-SSS4 3., 889999 4.-30 36'19 C,OJ.!.,5 ·0 300 2 8 • ': L, c; S c; 7 33.1ss9q7 4.911900 Q OoGl5J31C)0 3.,(;i~ssss J 4 " 2c:ss ss 23.65C.S38 0., 0 OoO Ou0 Oo7::i0000 6.,lbOUCO Oo0207759Cl Co021Ul i30 0 L, c; ,. f.2SSSC 1 0 ., 3 0 L~ CJ '-:J 9 0.0233 t'i 2DO 55 0~02tf.i 9jL0 59 ~C lSS ::i7 [,l. 83'i996 11..,62S S99 13.S4 0u00 Oo02 :5J:>990 9.370000 4 e,C SS9L+ Q,.02:)Y525J 01 .11 ssc;5 0 .. 0 4S6 13uG no ~ 1c;c;c:s1 1 5 l ~ f ~ c; S S !., iL u 5 8 ·J :J 'J Ci i) l 7 :-': • '\ C C C C C 0.0 1; •~0J6?'0 15~21':Vi9 9 l:.> .. 50 00J0 23,, 109S85 I+ 3 • 6 l c, 9 S' '> iS~ J '.) 99b S 67·. l.LJ')(d7 173 Table 3. Absorption Spectra a s a Function of Concentration for Rh(CNt-Butyl),1Cl i.n 0. 1 M NaCl/water c in moles/liter c .. n O.LCO]!.;lt'..O C.CCC '.'.;- ?322 C.1,r,cu1223 O.C017S?37 C.CC!f7-i;727 A 1 (3'71 nm) o.o 0 .. 03 <'.;G00 C .. 2<::8000 _o.01s2c1:~s 0.0232 53F.3 6.(3200 () 17.~?lL.f-7 1.,3 .. :.cc.?l+l t;. i. csz.:. SQ ___ 4 3 .. 3 2 7 L c, 9 63 .. qlc;cc.g 7,., .. C?.JLC.:, -i 3 .. 7 3 P. L. s ') 77e0C8,-~c; c:;7.41.5ccc; - 11 E., 53(;<; c.J. l47 .. S67«C9 C.02672600 163 .. zocc es 0.03073970 l97.0l24S7 OoUCP2~200 O.C0791G~O o.oc~::2:, r~6 0 .. 01157380 0 .. 0132CSCO 0.0122.::~co 0 .. 0.lVt?" 10 A 2 (490 nm) o.o Q.,l18t,OCO . . l.f.:J3<::S9 . 3.29SS~9 9.35?.200 1/~ ., 0 11 S :; 0 22. ?,0S<; ~8 22~3901,90 -22., E 29 SS 9 __ 20 .. csc?9Sl 32 .. 20~SS1 33. C7-6 S<;J 33 .. 02f..SS3 .A.3. S 7:J S S 6 _ 50 .. 31+9SS1 54 .. ll35C0 t3 .. 2(;SS£S 174 Results and Discussion A simplified energy level diagram for a monomeric d complex of the form Rh(CNR)/ is shovm in Fig1.ire l. 2 8 The level 2 2 ordering b 2 g(xy) < eg(xz, yz) < a 1 g(z ) << a 2u1r < b 1 g(x - y ) is based on that found for alkyl isocyanide complexes of square 8 13 planar ~ metal ions which have been recently studiect in detail. Ignoring spin orbit coupling, we eA'l)ect three spin allowed and 1 three spin forbid.den transitions from the A 1 g ground state. Spectra of dilute solutions of Rh(CNAlkyl)/ are all very similar and agree with the spectrum of Rh(CNEthyl) 4 • The band positions and the extinction coefficients depend only slightly on the nature of the alkyl group (Table 4). Absorption, emission, and excitation spectra of Rh(CNPh)/ monomer are shown in Figure 2. Band positions and assignments are given in Table 5. It is interesting to note that all MLCT transitions in Rh(CNPh)/ are red shifted relative to those found in the Rh(CNAlkyl)/ ions. 175 I I I l8? I w ---:v L LJJ RNC Figure 1. Molecular orbital diagram for Rh(CNR)/ showing the spect roscopica lly importa nt levels. 1 335 (3. 40) 310(25.5) Rh(CNt-butyl) 4 Clc c DetermL.'1.ed at room temperature in CH 2 Cl 2 • b Taken from reference 13. a nm ( E x 1o- 3 ). 338 (4.20) 310 (32. 8) Rh(CNcyclohexyl) 4 BPh4 c Eu 338 (3. 80) 3 310(28.0) A1g - Rh(CNi-propyl) 4 BPh/ l 333 (3.45) A1g - Eu 307 (24. 4)a 1 Rh(CNEthyl)/ b Complex l 386 (9. 90) 383 (11.8) 383(11.2) 380 (8. 40) A 10. - A2U 1 Table 4. Absorption Spectra of Alkyl Isocyanide Complexes of Rh(I) l 442 (O. 30) 442 (0. 39) 442 (0. 34) 434 (0. 26) 3 ~ - A2u - ;J 0) - 177 2.0....-------------------------------------. 1.0 LL] (.) z s De 400 GOO 700 WAV~L.ENGTH Figure 2. Curve A is the absorption spectrum at room temperature 6 of Rh(CNPh) 4 BPh 4 in acetonitrile, C = 7. 2 x 10- M, 1 cm cell; Curve B is the excitation spectrum of Rh(CNPh) 4 BPh4 in an EPA glass at '77 K; Curve C is the emission spectrum of Rh(CNPh) 3 BPh 4 in an EPA glass at 77 K. 178 • Table 5. Absorption Spectra of Different Salts of the Rh(Cl\J-Ph)./ Cation Compounda Intraligand Rh(CNPh) 4 BPh 4 1 1 l 1 l 3 A1g - Eu A1g - A2u A1g - A2u 241 (60. 5) 335 (40. 2) 411(5.00) 463 (0. 63) Rh(C1\TJ?h) 4 P F 6 241 (59 . 2) 335 (49.1) 411(5.94) 462 (0. 67) Rh(CNPh) 4 BF4 241 (59. 4) 335 (41. 7) 411 (5.71) 463(0.66) a Determined at room temperature in acetonitrile solution. 179 This shift is in line with tr.e stabilization of the a 2 un* acceptor orbita l via conjugation with the pheny l ring 7T system. This effect has previously been fou11d to be important in other complexes of . 1socyan1 . ·ct es. 14 aroma t 1c The shHt for each band in Rh(CNPh)/ relative to its counterpart in Rh(CNAlkyl)/ is not constant from band to band, suggef:;bng that slight energy shifts in the positions of the filled eg(dxy, dyz) relative to the a 1 g(dz 2) orbital also occur. The positions of the lowest spin allowed monomer band 1 1 A 1 g .... A2 u in complexes of p-ClPhNC, p-MePhNC, and p-MeOPhNC are very clos e to those found for Rh(CNPh)/· , suggesting a very slight dependence of the band positions on phenyl ring substituents. This fact suggests that de localization of the excited electron onto the phenyl ring is not a very important effect in these complexes. Rh(CNPh)/ was found to show strong emission in an EPA glass at 77 °K. Rh(CNAlkyl)/ cmnplexes also emit under these conditions but were not studied. The pos ition of the emission which occurs at 580 nm in EPA glass at 77°K in Rll(CNPh)/· is consistent with its assignment as 3 1 A 2 u ..... Aw. The r ed shift of the emission and the increase in the b ha lf width of the ban d rela tive to the correspondin g spin forbidden absorbance band implies that the emitting state is somewhat distorted - 15 from the ground state's squar e planar ge ometry. These effects lk'lve als o been observed 16 in [ Rh(2- pllos) 2 ] Cl and [ Rh(2=phos) 2 ] Cl. 180 Such an effect may be caused by admb,._1:ure of d-·Q. states into the charge transfer excited state. The excitation spectrum in EPA at 77 °K is very similar to the absorption spectrum revealing that 3 relaxation processes from upper excited states to the A2 u state _are facile. Representative absorption spectra for three different concentrations of [ Rh(CNPh) 4 ] (PF 6 ) in acetonitrile solution are shovln in Figure 3. The bands at 361, 411, and 468 nm dominate the low-concentration spectra and are logically due to monomeric [ Rh(CNPh) 4 ] + as discussed previously. As the total R.h(I) concentration is increased, two new bands grow in, first at 568, then at 727 nm, while the higher energy bands decrease in relative intensity. Similar concentration dependences of the spectral charges are obtained with the BPh 4 - and BF 4 - salts (Figure 4), suggesting that the spectral changes are a property of the cation only. This behavior is interpreted in terms of an oligomerization equilibrium: D 2M K2 D+IVI T where M == concentration of monomers, Rh(CNPh)/, D = concentration of dimers, (Rh(CNPh)/) 2 , T = concentration of trimers, (Rh(CNPh)/) 3 • Using the above equilibria expressions and the fact that the total concentration in terms of monomers must equal the weighted sum of all the species present, the follmving equations can be derived: 181 1.ol A LJJ u z < 0J (.L oCf) I 0.5r- I CI) <( nm--c::- 900 Figure 3. Absorption spectra of Rh(CNPh) 4 PF 6 in acetonitrile at 2 25 °C. A; C = 5. 7 x 10- M, path length= 0. 06 mm; B, C = 2. 7 x 10- 2 M, pathlength = 0. 06 mm, C, C 6. 3 x 10- 4 M, pathlength = 0. 75 mm. = I i 0 o! I I i i !i I.C~ I I wr /.;2 1 \ I I l II 3.0 f- 0 0 1.0 J d'+ . 0 2.0 • 0 + • CONC. 3.0 + 0 4.0 + 0 • 0 + = ~- 5.0 X 10-~ • = 5p;'°'4 + = BF;;- 0 e 6.0 I from Oto 6 x 10- 3 M for thr ee difforent salts. Figure 4 . Plot of A 2 (568 nm) vs. stoichiometric Rh(I) concentration ,L., + o o 0 0 0 0 + 0 0 0 0 0 0 1:-.:) O:> - 183 1) 3K 1 K 2 A 2 l C =--✓ E2K1 + E2 ✓E 2 K 1 C 2 .. 3/2 E3K2ffi Al 3/2 E2 where c is the total Rh concentration in terms of monomer, A2 , A 3 are the absorba.nces due to only dimers and trimers; and E 2 , E 3 are their corresponding extin.ction coefficients. The band at 568 nm is logically 1.ssigned to the dimer (A 2 ) and the band which grows in more highly concentration solutions at 727 nm is assigned to a trimer absorption (A 3). These assignments are supported below. A plot of c//A; y_§_. fp;; over the concentration range 2 5 x 10- M > c > 5 x 10- 4 Min 0.1 M [ (n-Butyl) 4 N] [PF 6 ] gives a straight line (Figure 5). At the higher concentrations where the band at 727 nm (trimers) is present, this line still shows no deviation from linearity suggesting that the third term in equation (1) is much s 1naller than the first two terms. From the intercept (1/✓E 2 K 1 ) and the slope 1 (2/ E 2 )values for K1 and E2 , K1 = 35 J'v.C and E 2 = 10, 500 are obtained. A plot of A3 vs A 2 3/2 ( eqn. (2)) (Figure 6) also gives a straight 2 line with the slope equal to E 3 K1 K2 /v'E 2 K~ E2 = 2. 92 x 10·· • Substituting in the values of K1 and E2 from eqn (2) give E3 K2 = 183,000. Thus a value of E: 3 of 18,300 (a quite reasonable value) will give K2 of 10 M. -l 184 /_j 5 _,_ _ _ _ 3 5 0 iO Figure 5. A plot of C/~ vs . .fA;, for Rh(CNPh) 4 PF 6 over the 2 range 5 x 10- M > C > 5 x 1 0- 1 M in O. 01 M 185 80 :- - - - - - - - - - - - --- -- - - - - - - ---:----, n i -~.~, ..::.. '. Figure 6. A plot of A 3 vs. A 2 3/2 for Rh(CNPh) 4 PF 6 in 0.1 M [(n -Butyl) 4 N] [ PF 6 ] /CH 3CN. 3000 186 The imp orta nt info r ma tion obtai_ned from thi.s equilibr ium da ta is tha t it appears the equilibr ium constant for addin g another mono me r unit to a dimer is simila r to that for the initia l fo r ma tion of the dimer. Thus the interaction behveen tv;o monomers and a monome 1' and a dimer app ear to be of comparable magnitude. The nature of the inte raction of the monomer units will be discus sed in a later section. Althou gh 110 evidence for oligomerization of alkyl isocyanide complexes of Rh(I) in acetonitrile was found, Rh(CNt- butyl) 4 Cl was found to oligomer ize in water solution . The absm~ption spectr a show similar concentration effects. The absorption due to the dimer was found at 490 nm with a band at 622 nm being assigne d to a trimeric species. The band at 622 nm is present in solution only near the solubility limit of the complex.. Concentration dependence data were not obtai11ed for this absorption band. Data obtained in 0. 1 M NaCl in water at 25 °C were 4 obtained over the r ange 3 x 10- M > C > 1. 6 x 10- M. A plot of 2 c//A;, vs. ffz (neglecting the third term in equation (1)) gives a 1 straight line with E 2 = 16, 900 and K1 = 251 IVC (Fi gure 7). Since the data were not obtained i.n the same solvent, a duect •comparison of the two equilibrium constants for Rh(CNPh)/ and RhCNt-butyl)/ cannot be made . The fact that dimer formation occurs i...11 water but not in a cetonitrile for Rh(CNt-butyl) / suggests that hydrophobic interactions of the lar ge alkyl groups serve as part of the driving forc e for di.mer formation in water. Also of importance 187 J ,.,_ 1 0 5 iO Figure 7. A plot of C/-[A.-;, vs. /A 2 for Rh(CNt-butyl) 4 Cl over the conc entration range 3 x 1O M > C > 1. 6 x 10 -2 0.1 M in 0. 1 M NaCl/H 2 O. - 4 M in 188 must be Lhe ability of the hi gher dielectric medium, water (> 85) vs. acetonitrile (36. 2) to stabilize the increase in charge density in going from two monopositive ions to one di.positive ion. The eJectronic spectral properties of [ Rh(CNR) 4 ] 2 2+ may be unde rstood in te nns of the orbital interactions diagrammed in Figure 8. As infrared s pectral evidence rules out the involvement of bridging 17 isocvanides the dimer is very probabl'Y boillld throuo-h diTect ,. ' b Rh•-- -Rh interactions. These bonding interactions apparently are substantial, as they must overcome unfavorable coulmnbic forces between the cationic units. The orbitals that will interact most strongly are. those that exte:i.d perpendicular to the molecular plane, namely the a. 1 g(dz 2 ) and a 2 u[ p 2 , 1r* (CNR) ] functions. It is also import1..nt to note that a 1 g is likely to be the HOl\10, and a 2 u the LUMO, in the monomeric units, as previously discussed. It is not likely that there will be a significant energy difference between D4 h (eclipsed) and D,1ct (staggered)rotameric configuratiC?nS for the dimeric molecules where R = Ph, but the staggered configuration is much more likely for the dimer when R = t-butyl. The :MO level scheme in Fig1.1re 2 gives symmetry larel s for both possibilities. In both cases the upper and lower sets contain orbitals of the same symmetry, and as a result there will be considerable mixh1g, stabilizing the lower set (la 1 g, 1a 2 u, or lau lb 2 ) and destabilizing the upper set (2a 1 g, 2a 2 '-l' or 2au 2,b 2 ). As the lower set is filled, this stabilization must be the source of the intermonomer binding forces. 189 D4h Figure 8. Relative energies of the molecular orbita ls derived 190 Tv✓ 0 allowed e lectronic trai1s itions are predicted for the dimer, one hi gher (la 1 g - 2a 2 u or la 1 (la 2u ..... 2a 1 g or 1b2 - 2b 2) and one lower 2a 1 ) than the a 1 g - a 2 u excitation in the monomer. Thus the bands at 568 nm in [Rh(CNPh) 4 ] 2 . 490 nm t1 [ Rh(CNt-Butyl) 4 ] 2 2+ 2+ and at are assigned to la2u - 2a. 1 g (or la 1 -- 2b 2 ). A simila.r ana lysis for a trimeric molecule predicts five allowed transitions, the lowest of v1hich (2a 1 g - 2a2u) is assigned . to the 727 nrn band i.n [ Rh(CNPh) 4 ] 3 3+ • The tr imer band is observed for Rh(CNt-- Butyl) 1Cl at 622 nm., In Table 6 are the locations of the lowest energy bands for the monomers, dimers, and trimer J of several Rh(I) isocyanide complexes. According to simple Hlickel theory, the dimer (E ) and 0 b:imer (ET) transition energies are given by: ED = EJl/f + (3; ET = EM + ·/'273; EM = E(a 1 g - a 2u) in the monomer, and (3 = f3a + (3a lg 2U • The results for two of the complexes for which absorption data for monomers, dimers, and trimers a.re availab le (R = Ph and i-propyl) are given i...11 T,:tble 7. The de creased value of {3 fo1· the alkyl isocyani.de vs. the aromatic isocya.nide suggests a smaller interaction between the monomeric unih3. 191 Table 6. Band J?os itions for the Lowest Spin Allowed Band for Ivfonomeric, Dimerie, an d 'I'rimeric Rh(I) Is oeyanide Complexes Complex Monomer -Dimer Trimer Solvent Rh(CNPh)/ 411a 568 727 CH 3 CN Rh(p-CNPhC1) 4+ 420 566 not observed DMF Rh(CNt-~ buty.l)/ 371 490 622 H 20 Rh(CNi-propyl)/ 383 49 5 610 H2 0 383 505 not observed CH 3CN 383 516 not observed CH 3CN Rh (CN eye lohe:\."Y 1) / a Peak maxima in nm. 192 Table 7. HUckel analysis of (Rh (CN Ph)_/ ) 1 and (Rh(CNi-propyl) 4 +) I a Comple x EM Rh(CNPh)/ 24.3b Rh(CNi-propy1) 4+ ED 26. 1b a Values expressed in kK. b Experimentally observed values. 1 c Calculated values taking (3 = 7100 cm- • 1 d Calculated values taking f3 = 6500 cm- • ll a ET a 17.2b 14.3b 17.6c 13.8c 20.0b 16.4b 19.6d 16.9d 193 References 1. D. S. M::artin, Jr., R. M. Rush, R. F'. K1-oening, and P. E. F'anwick, lnorg. Chem., 12, 301 (1973). -""- 2. K. Krogman, Angew. Chem. Internat. Ed., ~' 35 (J.9 69). 3. T. v,,r. Thomas and A. E. Underhill, Chem. Soc. Revs., 1, /'- 99 (1972). 4. H. R. Zeller, Adv. Solid State Physics, 13, 31 (1973). -""5. I. F. Shchegolev, Phys. Stat. Sol. (A), 12, 9 (1972). ~ 6. H. Isci and W. R. Mason, Inorg. Chem., 13, ____,..._ 1175 (1974). 7. K. Kawakami, IVI.. Haga, and T. Tanaka, J. Organometal Chem., 60, .,.__,.,_ 363 (1973) . 8. J. Chatt and L. M. Venanzi, ,_T, Chem. Soc. (A), 4735 (1957). 9. W. P. Weber, G. W. Gokel, and I. K. Ugi, Angew Chem. Internat. Edit., 1-}, 530 (1972). 10. [ Rh(CNPh) 1] Cl has been prepared previously by reaction of [Rh(CO) 2 Cl] 2 with CNPh (J. \V. Dart, M. K. Lloyd, R. Mason, and J. A. McCleve:rty, J-. Chern. Soc. Dalton, 2039 (1973)). 11. J. \V. Dart, M. K. Lloyd, R. Mason, and J. A. McCleverty, tT. Chem. Soc. Dalton, 2046 (19'73). 12. G. W. Haupt, J-. Opt. Soc. of Amer., ~ 441 (1952). 13. H. Isci and V./. R. Iviason, foorg. Chem., 0._, 913 (1975). 14. K. R. Mann, M. Cimolino> G. L. Geoffroy, G. S. Hammond, A. A. Orio, G. Albertin, and H. B. Gray, Inorg. Chim. Acta, 16, 9? (1976) . .,.-..,-.. 194 15. C. J .. Ballhaus en, N. Bjerrum, R. Din gle, K. Eriks, and C , R. Hare, Inor g. Che m. , -" 4, 514 (1965). 16. G. L. Geoffroy, IVL S. Wrighton, G. S. Hammond, and H. B. Gray, J. Amer. Chem. Soc., -"-" 96, 3105 (1974). 17. Solid s a mples of the PF 6 - and BPh 4 - salts of [Rh(CNPh) 4 ]+ 1 exhibit a single v(C ::::::N) ir absorption at 2150 cm - . A yellow CH 2 Cl 2 solution of the PF 6 - salt which contains monomeric 1 [Rh(CNPh) 4 ]+, has v(C = N) at 2160 cm- • Concentrated, blue solutions of the PF 6 - salt in acetonitrile also display a single 1 v(C = N) band at 2160 cm- • Neither the solids nor concentrated acetonitrile solutions exhibit any ir absorptions ,tttributable to bridging isocyanides. 195 CHAPTER 3 THE PREPARATION, SPECTRAL PROPERTIES AND OXIDATIVE ADDITION REACTIONS OF A DIMERIC Rh(I) ISOCYA:Nl:DE COMPLEX Rh 2 (bridge) 4 2+ 196 Introduction We have shown previous ly that cationic arylisocyanide complexes of rhodium(I) aggregate in solution throu gh formulation 1 of metal-metal bonds. The chernical behavior of these oligomer ic species should be quite interesting, as the opportunity for coupled electron transfer exists. In order to explore this possibilHy in a simple case, we have synthesized and char~cterized a dimeric . Rh(I) complex conta ining four 1, 3-diisocyanopropane (!::lridge) ligands. V✓e have found that this dimer aggregates still further in solution to form higher oli gomers, and that it undergoes two-center oxidative addition reactions v1ith several substrates. Expe r imental [ Rh(COD)Cl] 2 was synthesized by the method of Chatt, et al. 2 Solvents were spectrograde (CHC1 3 , CH 3OH, CH 3CN). 1, 3-diisocyanopropane, C 5H6N2, bridge. This ligand was 3 synthe s ized usin g the method of Ugi, et al. , and was purified by vacuum distillation. The P MR spectrum showed a complex multiplet at 3. 68 6 and a broa d peak at 1. 98 6 which inte grated in the ratio of 2:1. The infrared spectrum shows a very strong,narrow 11(CN) stretch 1 at 2140 cm- • Othe r prominent peaks are located at 2930 m, 1 GGO m, and 1490 s. [ Rh 2 (brid ge) 4 ] Cl 2 • This compound was obtained as a blue powder by adding a stoichiometric amount of bridge to a chloroform solution of [ Rh(COD)Cl] 2 • 197 Rh 2 (br idge) 4 (BPh.1) 2 • 2CH 3CN. A stoichiometric amount of NaBPh 4 in methanol was added to a methanol solution of Rh 2 (bridge) 4 Cl 2 . The purple solid was then rec rystallized from acetonitr ile. Cale: C, 66.37; H, 5.41; N, 10.75. - v(CN) 2172 cm -1 Found: C, 65.59; H, 5.49; N, 10.24. KBr pellet. PMR spectrum: broad singlets at 6 3. 780 and 1.986 in 2:1 ratio ind DIVISO. The peak due to acetonitrile was also observed. [Rh 2 (bri.dge) 412 ] [ Is) 2 • Synthesis ,vas accon~plished by 3,dd ition of 12 to a warm acetonitrile solution of Rh 2 (br idge) 1 (BPh 4 ) 2 • The product crysta llized as red crystals on cooling. Cale: C, 15. O; H, 1.50; N, 7.05; I, 63.5. Found: C, 15.8; H, 1.65; N, 7.0G; I, 62. 2. ii(CN) 2227 cm- 1 KBr pellet. [Rh 2 (bridge) 4 Br 2 ] (Br 3 ) 3 • Synthesis w·'as similar to I:: adduct above. Cooling the solution gave yellow crystals. Cale: C, 19. 67; H, 1..98; N, 9.17. Found: C, 19.97; H, 1.93; N, 9.06. D(CN) 1 2230 cn.1- KBr pellet. [Rh 2 (bridge) 4 (CH 3)(1)] (BPh1 ) 2 • 2CH 3 CN. A stoichiometric amount of CH 3l was a dded to a solution of Rh 2 (bridge) 1 (BPh 1 ) 2 • 2CH 3CN in acetonitrile. On slow 2-ddi.tion of diethyl ether, reddish brown crystals were obtained. Cale: C, 60. 66; H, 5. 09; N, 9. 69. Found: C, 58.74; H, 5.08; N, 9.29. ii(CN) 2183 and 2212 cm- 1 6 (KBr pellet). Pl\1R in d DMSO broad singlets at 4:. 08 o (terminal CI-I 2), 2. 186 (central CH 2 ), and a doublet at 1. 38 6 (CH 3). Peaks were also obs e rved for the acetonitrile protons and the tetr aphenylborate protons. 198 Infrared spectra were obtained as KB1· pellets on a PerkinElmer 225 spectrophotometer . Electronic absorption spectra were measured using a Cary 17 spectrophotometer. PMR spectra were record ed on a Varian A-60 spectrometer. Absorption spectral data for different concentrations of Rh 2 (bridge) 4 Cl 2 were obtained in CH 3OH using a short path.length cell 2 calibrated.4 with CrO 4 Supplementaxy Da.ta Absorption at 555, 778 and 990 nm as a function of Rh 2 (bridge) 1 Cl 2 concentration jn CH 3 OH. C A555 Ana Aggo 7.10 g/Q 35.97 81. 75 79.40 2. 84 g/Q 29.24 48.42 35.085 1. 30 g/.Q 18. 01 15.90 7.02 1. 04 g/ P.. 14.97 10 .29 4.21 0. 52 g/£ 9.82 2.34 0 .58 0.13 g/2- 1.76 0 0 Results and Discussion The chloride salt of the dimer, [Rh 2 (bridge) 4 ] Cl 2 , was obtained by addition of bridge to a stoichiometric amount of [ Rh(C 8 H 12 )Cl] 2 in chloroform solution. A blue precipitate was isolated and converted to a purple tetrapllenylborate salt by metathesis in methanol. The BPh4 salt was recrystallized from acetonitrile. The infrared spectrum of 1 a KBr pellet of the dimer exhibits one C= N stretch at 2172 cm- • There are no bands in the IR attributable to bridging isocya,nides. The 199 PMR sp ectrum of the dhner h-1 DMSO displays broa d singlets at 3 , 7 o (terrn inal CH 2 ) and 1. 9 o (central CH 2 ). As steric considerations rule out bidentate coordination by brid ge at a single Rh(I) center , we assm:11e that the structure of [ Hh 2 (bridge) 4 ] 2+ is as sho\m in (I): ({) Eiectronic absorption spectra for tlnr-ee different concentrations of [ Rh 2 (bridge )-1 ] Cl 2 in methanol are sho\m in Figure 2. Absorptions at 318, 342 , and G55 rnn arc the only bands observed at low concentrations of [ Rh 2 (b:ciclge),i] Cl 2 , and are lo gica lly assig11ed to the dimer [ Rh 2 (bridge) 4 ) 2+ , or D, itse lf. This assignment is supported by the ,:, l' •·- - .../ ••c, I ~ \ ' 1, i22J __ ~-c -;1: ~~ - /:7./'.) I ----_; ·--.,,,____~o---=-~ _ -:=::::.___ __ ~. -::::::::_ --~ -- _ _ _ _ I I i ! ~ . ~ 'c-.., :· . .. Figure 2. Absorption spectra of Rh 2bridge 4 Cl2 L.1 methanol. Top curve C = 1 . 3 g/ Q in O. 2 mm cell; middle curve 0. 52 g/ Qin 0. 2: mm cell; bottom curve 0.13 g/ Q ub 1 mm cell. I',\\_ \ /// \:\ \>,-' :-::,,__ _____ ___ _,_,,f - ~-::. O•·- - - . -,,.. ___ c:_·..---- - - - - - ·- ---- - - - - ·-- -- ---- -·--- - ·; :! i J :1 i1 ·~} Li :. ) 'i ~ r -·~ !,1 \i :! d L _, D [}:]:;}) ( 0 c:·r>D .Jfd 7 fi~;(J1 :J\\ i!:j •:\ ! ,1'1 I I I 1•I I ! ~- I ,r:1 i !\ '- ... . 1.. (I _1,·, .' ;j·' :... /,,' . 0 0 to., 201 observation that absorptions owing to [ Rh(CNPh) 4 ] 2 2+ and Rh(C l'f..t?h)/ are reported, respectively, at 568 and 411 nm in 1 acetonitr ile solution. As the solution becomes increasingly concentrated, principal low energy bands appear at 778, 990, 1140, and 1735 nm. The conc entration dependence of the absorption spectra may be interpreted in terms of the following equilibria: Dn+l 2D 2 3 A plot of (A 555 ) ys. JJC;;-; is a straight li.112, as is A 555 vs. .p:;;;;; , indicating that the bands at 778 and 990 nm be assigned to tetrameric and hexa,meric R.h(I) species. The bands at 1140 and 1 735 nm are present only in the most concentrated solutions, and are logically attributable to higher oligomers (n > 3). The observed spectroscopic behavior of the [ Rh 2 (bridge) 4 ] 2+ oligomers accords with simple MO theory (Figure 3). The 555 nm absorption ma y be assigned to the fully allowed la2U - 2a 1 g transition, 1 by analogy to the 568 nm band observed in [ Rh(CNPh) 4 ] 2 2+. Similar analys is of the tetrameric Rh(I) units suggests that the 778 nm bands be assigned to 2a 2 u ...., 3a 1 g, and the hexa meric Rh(I) absorption at 990 nm be assi gned to 3a 2 u - 4a 1 g. The band at 1140 nm is attributed to 4a 2u - 5al0' in an octam.eric species (n = 4). i:-, 2 The straight li11es obtained for (A 555 ) vs. .../A 778 and (A 555 ) vs. 3 ✓--A:;;0 (Figures2 and3)have slopesof3.'72and 7.96,respectively, where the slope of the first line is equal to E555 //K 1 E 2 and the second equals E555 /--/KJ{;T3 • E 555 is equal to 14 1 500 from measurements on dilute solutions of Rhz{briclgetBPh,1 • 2CH 3 CN. in CH3CN. Thus K 1 E2 == 202 7 l. 52 x 10 and K K E 1 for E 2 2 9 :::: 3 6. 04 x 10 . Assuming reasonable values (29,000) and E: (43,500) gives K 3 524 M- and K 1 :::: 1 :::: 2 265 M- 1 • These estimated values for E 2 and E 3 are reasonable since work on other similar systems l, 5 show that the extinction coefficient for the lowest band in the dilner is approximately the sum of the extinction coefficients for the monomers. Because of the empirical nature of this approximation, these values should be viewed with caution. However, they are probably withLri ± 50% of the correct values. The equilibrium constants are also similar to those fow1d in other Rh(I) systems where they have been measured. 6 According to simple Hlickel theory, the tetramer, hexamer, and actamer transition energies are given by: ED 2 ED 3 = ED + /3; = ED + -fZ"/3" ; ED4 = ED + ../5 + 1 /2; ED = E (la 2u - 2a 1 g) and /3 = /3 1a 2 u + {3 2 a 1 g. Theory and experiment accord closely 1 for f3 = 550 cm- : En (calcd) = 12,500, ED (obsd) = 12,820; 2 2 ED (calcd) = 10,220, ED (obsd) = 10, 080, ED (calcd) 3 3 4 = 9100, ED (obsd) = 8770 cm - l . The broad absorption system centered at 4 1 about 1735 nm (5760 cm- ) probably represents overlapping bands a-wing to oligomers with n > 4. ED+ 2f3, or 7000 crn -1 For N = co, the calculated limit is . The (3 internal ({3 between the two Rh atoms of the dimer) can be calculated from ED = EM + ,Bi.nt' where EM can be estimated 1 6 from the monomer transition in Rh(CNi-propyl) / (EM =26, 100 cm- ). Since ED = 1 18,000 cm- , /3. ,_ == 8100 cm - l . Comparing this value llll 203 1 with the (3 betv1reen dimers (5500 cm ~ ) suggests that the Rh a.tom interaction is stronger in the dimer unit than that between the units. Oxidative Addition Reactions Upon addition of 12 to dilute acetonitrile solutions of [ Rh 2 (bridge) 4 ] (BPh4 ) 2 } oxidation to a diiodo adduct, [ Rh 2 (bridge) 412 ] takes place immediately. 2+ , The product wa,s isolated as a red triiodide salt. This oxidative addition product presumably conta ins two Rh(II)1 units connected by a single metal-metal bond. In terms of the MO formulation of the metal-metal interacti. on in [ Rh 2 (bridge) 4 ] 2+ , the two electrons in the la 2 u orbital are tro,nsferred to the two I ato1ns to give two I - 2 groups and a Rh(II)-Rh(II) bond (la 1 g) . The infrared spectrum of a KBr pellet of [Rh 2 (bridge) 4 12 ] (1 3 ) 2 exhibits a single 1 C=N stretching frequency at 2227 cm - , indicating trans I-Rh(II)Rh(II) - (1) stereocheraistry, as would be expected. The higher C=N 2+ frequency observed fo r [ Rh 2 (bridge) 4 12 ] [ Rh 2 (bridge) 4 ] 2+ as compared to that for is consistent with the Rh(II) formulation of the diiodo adducts. \Vhen the 12 oxidation was performed at high concentrations of [ Rh 2 (bridge) 4 ] 626 nm). 2-f, a green intermediate species was observed (.\max = The concentration of this intermediate was maximal for the stoichiometric ratio 2[ Rh 2 (bridge) 4 ] 2+ : 12 • Furthermore, the concentration of the intermediate was found to be proportional to [ [ Rl1 2 (bridge) , ] 2+ 2 ] . The green species is formulated as [I-D-D-1] 4+ . 204 Similar chemistry was observed when Br 2 was used as the oxidant yielding [ Rh 2 (bridge) 4 Br 2 ] (Br 3) 2 • Interestingly, the Br 2 oxidative addition is thermally reversible in either acetonitrile or DMF- wate r solutions, and is therma.lly reversible in either acetonitrile or DMF-water solutions, and blue [ Rh 2 (bridge) 1 ] 2+ may be recovered or may be reoxidized with the addition of further brom.ine. A green species similar to that observed for the 12 oxidation was alsc observed (>\.max = 595 nm in DMF) but no concentration dependence data were obtained. Addition of methyl iodide to [ Rh 2 (bridge),J (BPh 4 ) 2 in acetonitrile solution, yields a yellow solution containing trans-[ Rh 2 (bridge) 4 -(CH 3) (I)] 2+ . The CH 31 adduct was isolated as reddish brown crystals of a tetra.p henylborate salt by slow a,ddition of diethyl ether. The infrared spectrum of the trans-[Rh 2 (bridge) 4 (CH 3)(1)] 2+ exl1ibits C===N stretches at 2183, and 2212 cm -1, which is consistent with the structural formulation The PMR spectrum of the adduct exhibits broad singlets at4.0, 2.1, and 1.3 6. As the resonance at 1.3 o does not correspond to any feature in unoxidized [ Rh 2 (bridge) 4 ]2; it is therefore attributed to a methyl group bonded directly to rhodium. The observa- tion of a 1-2 Hz sp litting of the 1. 3 ·6 resonance owing to coupling to the 103 Rh nucleus confirms the assignment. Integration of the spectrum indicates that the compound contains only one methyl group per dimer~ whic h is consistent with the proposed trans 2+ [ Rh 2 (br idge) 4 (CI-l 3)(I)] structure. 205 The electronic absorption spectrum of [ Rh 2 (bridge),il 2 ] z+ in acetonitrile solution exhibits intense bands at 465 (E 23, 200) and 397 nm (E 62,000). The very intense 397 nm band is logically attributable to the a - a* trans ition (1a 1 !?; - la 2u) in the Rh(II)-Rh(II) single-bonded species. Similar ly intense a --- a* bands in this 7 energy region have been observe d for Mn 2 (CO) 10 as well as 7 7 numerous other d -d metal-metal bonded complexes. The band at 465 nm could be due to one or more rlrr --- a* (la 2u) transitions, again by analogy to Mn 2 (CO) 10 • Intense bands at 438 a.nd 373 nm in [ Rh 2 (bridge) 4 Br 2 ] ~ and 470 and 397 nm in [ Rh(bridge) 4 (CH 3)(I)] ~ ~cetonitrile solution) presumably represent the dTr ...... a* and a ...... a* transitions, respectively, in these adducts. It is reasonable to expect that the la 1 g orbital will be delocalized to some extent over the X-Rh-Rh-X unit, and as a result the la 1 g ...... lazu in the [Rh 2 (bridge) 4 Br 2] 2+ complex is consistent with the proposed fractional charge transfer character. The mechanism of oxidative addition to [ Rh 2 (bridge) 4 ] under study. [Rb2(bridge )4] 2+ is \Ve have found that the rate of C 2H5I addition to 2-1- is comparable to that of CHJ, and that CH 3OTs reacts eil..'i:remely slowly. V✓e suspect from these results that the initial step involves Rh(l) attack on a heavy atom in the substrate, yielding [Rh 2 (bridge)<1I] 2+ and methyl radical in the case of CH 3I. 206 References and Notes 1. K. R. Mann, J. G. Gordon, II, and H. B. Gray, J. Amer. Chem. Soc., .,,.__,..._ 97, 3553 (1975) . 2. J. Chatt and L. M. Venanzi, J. Chem. Soc., 47~i5 (195 17). 3. I. Ugi, ed., 11Isonitrile Chemistry, 11 Academic Press, New York, 1971. 4. G. w·. Hampt, J. Opt. Soc. of America, ~' 441 (1952). 5. H. Isci and V✓. R. Mason, Inorg. Chem., 13, .,,.__,..._ 1175 (1974) . 6. This thesis, Chapter 2. 7. R. A. Levenson and H. B. Gray, J. Amer. Chem. Soc., 97, ~ 6042 (1975). 8. Complexes of the type [ Rh 2 (CNR) 2 X2 ] solutions of [ Rh(CNR) ] 4 z+ obtained by m.ixing + and trans-[ Rh(CNR) X + (R = alkyl; ] 4 2 X = halide) have been reported [ A. L. Balch and M. M. Olmstead, J. Amer . Chem. Soc.,~' 2354 (1976)]. These adducts exhibit electronic spectral properties that are very similar to those of analogous [ Rh 2 (bridge) 1 X2 ] for [ Rh 2 (CNR) 8 X2 ] 2+ 2+ complexes. Of the two structures species suggested by Balch and Olmstead our results favor the one containing a dir ect Rh(II)-Rh(II) bond in preference to the Rh-X-Rh-X alig11ment. Balch and Olms tead also argued that their spectral data were more consista.1 t with a Rh(ll) ··Rh(II) bonded species.