The molecular structure of silyl monothioacetate in the crystal at 130 K and in the gas phase

Abstract

The structure of SiH₃OCSCH₃ has been determined in the solid by X-ray diffraction and in the gas by electron diffraction. At 130 K crystals are monoclinic, space group P2₁/n, with a= 5.40, b= 8.77, c= 11.47 Å, β= 96.0°(estimated standard deviations 0.3% assumed), and Z= 4. The final R value was 0.032 over 739 reflexions. The silyl group is bonded through oxygen: Si–O 1.699(5)Å(crystal) and 1.717(6)Å(gas). The Si–O and CS bonds are eclipsed so that the intramolecular Si ⋯ S separations, 3.185(9)Å in the crystal and 3.143(9)Å in the gas, are appreciably less than the van der Waals distance. The heavy-atom skeleton deviates slightly, but significantly, from planarity in the crystal, where ϕ(Si–O–CS)=–6.0(4)°. In the gas this torsion angle is ca. 10°. Interactions between neighbouring molecules in the crystal are consistent with weak secondary bonding between S and Si. The intermolecular CS ⋯ Si–O systems have geometry: S ⋯ Si 3.382(10)Å, CS ⋯ Si 100.8(4)°, and S ⋯ Si–O 166.3(3)°.