X-Ray Studies of Organo-Bismuth Compounds and Caryophyllene Derivatives

Hawley, David McKill (1969) X-Ray Studies of Organo-Bismuth Compounds and Caryophyllene Derivatives. PhD thesis, University of Glasgow.

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This thesis is divided into three parts. In the first, some aspects of the theory and methods of X-ray Crystallography are introduced and briefly discussed. The second and final parts are concerned with the applications of these methods in the elucidation of the crystal structures of four molecules. Accounts of the structural analyses of triphenyl-bismuth, (C6H5)3Bi, and triphenylbismuth dichloride, (C6H5)3BiCl2, are contained in Part II. It has been established that the triphenylbismuth molecule is pyramidal with virtually no hybridisation of the 6s and 6p orbitals of the bismuth. The expected symmetry has been destroyed by the asymmetric rotations of the phenyl groups about the Bi-C bonds. The proposed trigonal bipyramidal structure for triphenylbismuth dichloride has been confirmed by a crystal-structure analysis. The more electronegative chlorine ligands occupy the apical positions with the phenyl groups attached equatorially to the central bismuth atom. Again the molecule possesses no overall symmetry as a result of the unequal rotations of the benzene rings with respect to the equatorial plane. Part III describes the analyses of two caryophyllene rearrangement products, viz., caryophyllene 'iodonitrosite' and the mono-p-bromobenzenesulphonyl ester of the diol derived from pseudoclovene-A. The former belongs to the relatively new class of stable aliphatic nitroxide radicals, and has an N-O bond length of 1.308 A which corresponds to a three-electron bond. The absolute stereochemistries of both derivatives have been established by means of Bijvoet's anomalous dispersion method. Fairly detailed accounts of the conformations of these molecules are given and the ways in which they have undergone distortions, to avoid the severe inherent strain associated with these species in their classical conformations, are discussed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Organic chemistry
Date of Award: 1969
Depositing User: Enlighten Team
Unique ID: glathesis:1969-78497
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:14
Last Modified: 30 Jan 2020 15:14
URI: https://theses.gla.ac.uk/id/eprint/78497

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