An X-Ray Diffraction Investigation of Silver Azide and Boric Oxide and an Electron Diffraction Investigation of Some Three-Membered Rings and Some Halogenated Methanes

Author: Pfeiffer, Heinz Gerhard

Year: 1949

Degree: Dissertation (Ph.D.)

Advisors: Hughes, Edward Wesley; Schomaker, Verner F.; Pauling, Linus

Committee Member: Unknown, Unknown

Option: Chemistry; Physics

DOI: 10.7907/qrgh-1m86

Abstract

Sections I and II report the X-ray diffraction investigations of silver azide and boric oxide. Silver azide crystallizes in a body-centered orthorhombic structure. The space group is Ibam with four molecules in the unit cell. The silver atoms are in (a), the central nitrogens in(~), and the end nitrogens in (j) with x = 0.156 and -y: 0.369. A new type of part cell projection is developed. Boric oxide crystallizes in a hexagonal structure with three molecules in the unit cell, ao = 4.320 Kx., co = 8.139 Kx. Each boron has three bonded oxygen neighbors at a distance of 1.35 Å and coplanar with the boron.

Sections III and IV report electron diffraction investigations of some three-membered rings and some halogenated methanes. The HCH bond angles of cyclopropane are about 116°, the C-H distance 1.10 Kx., and the C-C distance 1.515 Kx. The other three-membered rings...ethylene imine, ethylene oxide, ethylene sulfide, and N-methyl ethylene imine...have HCH angles of 116° and all other distances close to the sum of the covalent radii. The halogenated methanes... difluorobromomethane, trifluorobromomethane, trichlorobromomethane, and difluorodibromomethane...have bond angles close to tetrahedral; the only significant deviation is the FCBr angle of 110.5° in trifluorobromomethane. The bond lengths in these compounds are close to the sum of the covalent radii with the exception of the C-Br in difluorodibromomethane (1.925 Kx.) and in trifluorobromomethane (1.89 Kx.).

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