AbstractsChemistry

The primary aim of this investigation was to determine the structure of the compound CsReCl₄ by X-ray methods. This led to the discovery of the [Re₃Cl₁₂]³- anion and then, through another X-ray crystal structure analysis, to a determination of the structure of the [Re₃Cl₁₁]²- anion in the compound (Ph₄As)₂ Re₃Cl¹¹. Photographs of models of both anions are shown in the frontispiece. As part of this work the author helped to establish a system of progress which enable the formidable calculations necessary for most crystal structure analyses to be carried out on an IBM 1620 computer. He also investigated certain aspects of the Buerger procession method and applied this photographic technique, with considerable success, to the complex problem of indexing Weissenberg photographs on a triclinic crystal. In this thesis two chapters are devoted to each of the crystal structure analyses. They contain little rigorous theory and no mention of the methods used to calculate various results. Theory is adequately described in many textbooks, and the methods, which were common to both analyses, are described and criticised in the last chapter on the computing system. Similarly, well established experimental methods are not described at all, but a detailed discussion of new photographic techniques is given in chapter V. Because some material has been referred to in several places in the text, it has been found useful to collect most diagrams, Fourier maps, structure factor listings and other tables in a separate volume of appendices. It is hoped that separating the accounts of the crystal structure analyses from the detailed reports of experiments and computations has resulted in the reader being presented with a clear record of the steps taken in solving these structures. Throughout the text symbols have been used with the meanings ascribed in International Tables for X-ray Crystallography, Volume 1, p.xi.