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The Structure of Tri(cyclohexyl)tin Chloride between 108 and 298 K:  A Compound in Which Molecular Dimensions Vary with Temperature

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posted on 23.05.2003, 00:00 by Ashrafomolouk Asadi, Colin Eaborn, Peter B. Hitchcock, Margaret M. Meehan, J. David Smith
Care is necessary when relating physical data obtained at one temperature on compounds showing significant intermolecular interactions to X-ray data obtained at other temperatures. This is revealed by the determination of the structure of tri(cyclohexyl)tin chloride at nine different temperatures between 108 and 298 K. In the crystal, the molecules pack in chains parallel to the c axis with the Sn and Cl atoms close to the plane, with y = 0.25. At low temperature, successive molecules in the chain are related by the glide plane in space group P21/c, and there is significant intermolecular interaction. As the temperature is raised, the Cy3SnCl···Sn interactions weaken and the intramolecular Sn−Cl bonds strengthen. At about 248 K, there is an order−disorder transition to space group P21/m with the c axis halved, and at room temperature the structure is best described as comprising discrete molecules, as previously reported. Thus, some of the molecular dimensions, in particular the Sn−Cl bond lengths, are not constant but are functions of temperature.