THE CRYSTAL-STRUCTURE DETERMINATION OF DIMETHYLSULFIDE BY HIGH-RESOLUTION NEUTRON POWDER DIFFRACTION

The crystal structure of perdeuterated dimethylsulphide, S(CD3)(2), ha s been solved ab initio from high-resolution neutron powder diffractio n 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 ha rnessing the anisotropy of the cell expansion with temperature has bee n used in order to improve the reliability of extracted intensities fo r the Direct Methods solution, especially in regions of severe peak ov erlap in the powder pattern. The structural results are discussed in r elation to recent NMR experiments investigating the reorientational qu antum tunnelling of methyl groups at low temperature. In particular, c onclusions are made regarding the degree of coupling between individua l methyl rotors. (C) 1997 Elsevier Science B.V.