Crystal Structure Studies by X-Ray and Neutron Diffraction

Dunlop, Robert S (1973) Crystal Structure Studies by X-Ray and Neutron Diffraction. PhD thesis, University of Glasgow.

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Abstract

This thesis is concerned with the study of crystal structures by x-ray and neutron diffraction techniques, and also with the application of the symbolic addition method of solving crystal structures directly from the diffraction data. Chapter 1 contains a review of direct methods of phase determination in diffraction experiments, the first part of the chapter being concerned with the historical background of the topic and the second part with the practical details of the symbolic addition method as applied to both x-ray and neutron diffraction data. In Chapter 2, the crystal structure analysis of the stable free radical t-butylferrocenyl nitroxide is described, and the possibility of direct Fe...N or Fe...O bonding is discussed. The relative orientations of the two cyclopentadienyl rings are compared with the orientations of the cyclopentadienyl rings in other ferrocene derivatives, and the dimensions of the nitroxide radical are compared with those published for other nitroxide radicals. Chapter 3 describes the refinement of the structure of the 1:1 complex of hexahelicene with 4-bromo-2,5,7-trinitrofluorenone, and the resulting dimensions of the hexahelicene molecule are compared with those predicted from molecular-orbital and valence-bond calculations in which a planar molecule was assumed. In Chapter 4 the determination of the crystal structure of potassium tri-hydrogen di-succinate directly from neutron diffraction data is described and discussed; the refinement of the structure of potassium tri-hydrogen di-glutarate is described, and the structures of these 'super-acid' salts are discussed, in particular the dimensions of their hydrogen bonds. Chapter 5 describes the x-ray and neutron diffraction analyses of the crystal structure of the neutral salt a-picoline N-oxide hydrochloride monohydrate, and the structure is described in terms of the disproportionation of a neutral salt into an acid salt and a basic salt. Particular attention is paid to the discussion of the 'acid salt' part of the structure,the bichloride ion Cl-H-Cl-. In Chapter 6, the structure analyses of the p. nitrosoaniline derivatives 9-nitrosojulolidine and N,N-diethyl p-nitrosoaniline are described, and the extent to which quinonoid-type structures contribute to the resonance hybrids of these compounds is discussed. The dimensions of their nitroso groups are discussed and compared with those of other nitroso compounds. (The accuracy attained in the neutron analysis of the picoline salt was disappointing in relation to the chemical interest of this structure. It could have been improved had it been possible to use longer counting times.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Physical chemistry, Analytical chemistry
Date of Award: 1973
Depositing User: Enlighten Team
Unique ID: glathesis:1973-78629
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:07
Last Modified: 30 Jan 2020 15:07
URI: http://theses.gla.ac.uk/id/eprint/78629

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