The crystal structure determination of dimethylsulphide by high-resolution neutron powder diffraction

The crystal structure of perdeuterated dimethylsulphide, S(CD3)(2), has been solved ab initio from high-resolution neutron powder diffraction data at low temperature. The structure is triclinic, space group <P(1)over bar>; V-c = 179.31 Angstrom(3) at 5 K and Z = 2. A technique harnessing the anisotropy of the cell expansion with temperature has been used in order to improve the reliability of extracted intensities for the Direct Methods solution, especially in regions of severe peak overlap in the powder pattern. The structural results are discussed in relation to recent NMR experiments investigating the reorientational quantum tunnelling of methyl groups at low temperature. In particular, conclusions are made regarding the degree of coupling between individual methyl rotors. (C) 1997 Elsevier Science B.V.