Structural Studies of Binuclear Cobalt (III) Cyano Complexes

Author: Fronczek, Franklin Robert

Year: 1975

Degree: Dissertation (Ph.D.)

Advisor: Schaefer, William P.

Committee Member: Schaefer, William P.

Option: Chemistry

DOI: 10.7907/wc2q-8t48

Abstract

The crystal structures of six closely related binuclear cobalt(III) complexes have been determined by single crystal X-ray diffraction methods, in order to study the effects of the pentacyano system upon the bonding to various bridging ligands. Studies pertinent to dioxygen bridging ligands include the bis(pentacyanocobalt(III)) structures K5{(CN)5Co2(CN)5}·H2O and the double salt K8{(CN)5Co2(CN)5} (NO3)2·4H2O, as well as the bis(pentaamminecobalt(III)) structure {(NH3) 5Co2(CN)5}(SCN)4. In all cases, the dioxygen ligands (peroxo and superoxo) are found to bridge to two cobalt atoms in the asymmetric, staggered arrangement, and both planar and nonplanar structures are noted. The structures of two molecules of the type pentacyanocobalt(III)pentaamminecobalt(III) are determined, with the bridging ligands cyanide and thiocyanate. These compounds are (CN)5CoNCCo(NH3)5·H2O and (CN)5CoSCNCo(NH3)5·H2O. The preparation and structure of the compound K6{(CN)5Co2(CN)5}·6H2O, containing the new bridging ligand thiosulfite (SSO22-) are reported. This ligand bridges the two cobalt atoms through its two sulfur atoms, and has a geometry similar to that of normal coordinated sulfites. Coordination to cobalt is trans planar.

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