The structures of four inorganic compounds have been determined by single-crystal X-ray diffraction methods. Three of the structures investigated were phosphonitrilic derivatives: octamethylcyclotetra-phosphonitrilium trichlorocopper(II), [NPMe₂]₄H.CuCl₃, bis-(octa-methylcyclotetraphosphonitrilium) tetrachlorocobaltate(II), [(NPMe₂)₄H⁺] ₂ CoCl₄²ˉ , and hexadecamethoxycyclo-octaphosphonitrile, [NP(OMe)₂]₈. The fourth analysis was a study of the ionic compound caesium difluorophosphate. For each structure determination the intensity measurements were collected on a diffractometer using a scintillation counter and Mo-K̲⍺ radiation. The structure of [NPMe₂]₄H.CuCl₃ was determined from Patterson and Fourier summations. Refinement of positional and thermal parameters of the atoms was by least squares. The structure consists of discrete molecules in which the eight-member phosphonitrilic ring approximates the "tub" conformation with pairs of adjacent phosphorus and nitrogen atoms displaced alternately above and below the ring plane. A ring nitrogen atom is bonded to the copper atom (N-Cu = 2.04 Å) which has three chlorines arranged about it in a distorted square planar configuration. Across the ring from the N-Cu bond, there is a protonated nitrogen atom which is hydrogen-bonded to a neighbouring chlorine. The phosphorus-nitrogen bond lengths are not equal around the ring, but occur instead in four distinct pairs having lengths 1.63 Å, 1.60 Å, 1.56 Å, and 1.67 Å. These varying bond distances are explainable in terms of π-bonding systems. The structure of [ (NPMe₂)₄H⁺] ₂CoCl₄²ˉ has been determined by Patterson and Fourier methods and refined by least-squares. Most of the methyl hydrogen atoms were located in a final difference Fourier summation. The structure consists of tetrahedral CoCl₄²ˉ ions hydrogen-bonded to two protonated phosphonitrilic rings. The N-H...C1 distance in each case is 3.21 Å. The two independent rings have slightly different conformations. One approaches the "tub" shape and the other tends towards the "saddle" conformation. Protonation of the phosphonitrilic rings again results in non-equivalent P-N bond lengths. Averaged values for the two rings are 1.69 Å, 1.54 Å, 1.61 Å and 1.58 Å. Parameters which are unaffected by the addition of the proton agree with those found in related compounds when averaged values are considered. [NP(OMe)₂]₈ is a centrosymmetric sixteen-member phosphonitrile. Its structure was determined by Patterson, electron density, and least squares techniques. The phosphonitrilic ring consists of two approximately planar and parallel six-atom segments joined by a step. The P-N bond lengths are all equal within experimental error, their mean being 1.561 Å. The average P-0 and 0-C bond distances are 1.576 Å and 1.440 Å respectively. The methoxy groups cover the ring evenly, their arrangement being such that there is little conflict between steric and π- bonding requirements. The structure of caesium difluorophosphate was determined by comparison with KPO₂F₂ and refined by least square methods. Caesium and rubidium difluorophosphate are isomorphous with the potassium salt; all have the barium sulfate structure. The mean P-F distance in CsP0₂F₂ is 1.58 Å, the P-0 bond length, 1.48 Å. The lattice parameters and interionic distances increase with increasing radius of the alkali-metal cation. / Science, Faculty of / Chemistry, Department of / Graduate

The preparation of the β-keto lactones 1̲9̲ via intramolecular alcoholysis of hydroxy Meldrum's acid derivatives was examined. Good yields of the 6- and 14-membered compounds were obtained, but the method was completely unsuccessful for medium-size rings. An investigation was conducted on the conformational preference of substituted 14-merabered lactones with a view to understanding the stereochemical consequences of the reactions of these compounds. The conformational preferences of simple 14-membered cyclic compounds were first determined. These preferences are described in terms of steric and electronic interactions, with the support of computer-calculated steric energies. A number of 14-membered lactones were prepared, beginning with the β-keto lactone 3-oxo-13-tetradecanolide (1̲3̲8̲). Hydride reduction of (1̲3̲8̲) gave the diastereomeric alcohols 1̲4̲6̲ and 1̲4̲7̲, which were then elaborated to give a series of derivatives. The stereochemistry and conformations of these compounds were determined by X-ray crystallography and/or nmr analysis. The preferred conformation was found to be Dale's [3434] diamond lattice model. The relative rates of reaction were determined for several reactions of the alcohols 1̲4̲6̲ and 1̲4̲7̲ and for one reaction of the corresponding acetates. The conformational effects were found to be much smaller than those observed in 6-merabered rings. Explanations of this difference are given. The preparation of the ⍺, β-unsaturated lactones 1̲6̲3̲ and 1̲6̲4̲, the β-methyl-⍺, β-unsaturated lactones 1̲8̲5̲ and 1̲8̲̲6̲̲, the dimethyl lactones 1̲5̲4̲ and 1̲5̲5̲ and the epoxides 1̲9̲7̲ and 1̲9̲8̲ are described. The resulting geometry of double bonds and the stereochemistry of substituents are explained in terms of conformational preferences. [Formula Omitted] / Science, Faculty of / Chemistry, Department of / Graduate

Macrocyclic polyether sulfides have been prepared by reacting an oligoethylene glycol dichloride with a dithiol in refluxing basic ethanol. The following new compounds were prepared: 1,5-dithia-(19- crown-6), 3-hydroxy-1,5-dithia-(19-crown-6), 1,4-dithia-(21-crown-7), 3-hydroxy-1,5-dithia-(22-crown-7), and 1,4-dithia-(24-crown-8). One other previously reported macrocyclic polyether sulfide was also prepared. The thesis includes a review of macrocyclic sulfides and other related compounds, the thermodynamics of interaction of several macrocyclic polyether sulfides with Ag^+, Hg^2+, and Pb^2+ ions, and a discussion of the structure of these materials.

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published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 59-62.

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 336-357). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references.

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