Structural and vibrational properties of ClC(O)SY compounds with Y = Cl and CH3

The structures and conformational behaviour of the sulfenyl carbonyl compounds ClC(O)SCl and ClC(O)SCH3 have been investigated in the gas and crystalline states by a combination of quantum chemical (HF, MP2 and DFT approximations with the 6-31+G* basis set) calculations, IR studies of the matrix-isolated molecules, and X-ray crystallographic analysis of single crystals at low temperatures. Hence the predominance of the syn rotamer in the vapour of each compound has been confirmed; the anti rotamer must account for less than 1% of the vapour molecules. The crystals of the compounds are each composed exclusively of the planar syn rotamer with overall Cs symmetry.