THE STRUCTURE OF (CH3)(3)SI3 - COMPARISON BETWEEN THE STRUCTURE IN THE SOLID AND LIQUID-STATE

The crystal structure of Me(3)SI(3)(s) has been determined. The compound is monoclinic and crystallizes in the space group Cc (No. 9) with unit cell parameters a=7.856(2), b=17.733(6), c=8.259(2) Angstrom, beta=111.14(2)degrees, U=1073(1) Angstrom(3) and Z=4. The structure contains pyramidal Me(3)S(+) cations and almost centrosymmetric I-3(-) anions. The near-D-infinity h symmetry of the triiodides is verified by Raman spectroscopy, revealing one single peak at 110 cm(-1). The local structure of Me(3)SI(3)(1) at 50 degrees C and the sulfonium-triiodide coordination mode, as characterized by liquid X-ray scattering and Raman spectroscopy, is almost identical to that in the corresponding solid and the analogous Et(3)SI(3) melt. The difference in sulfonium hydrocarbon chains induces very minor changes in the local structure of the trialkylsulfonium triiodides both in the solid and molten state. X-ray absorption spectroscopy, XANES, of the S-K edge reveals electronically identical sulfur atoms in solid and liquid triiodides, which also implies a similar local structure.