CONFORMATIONAL PROPERTIES OF METHYL VINYL SULFONE - AB-INITIO GEOMETRY OPTIMIZATION AND VIBRATIONAL ANALYSIS

An ab initio conformational analysis of methyl vinyl sulfone (CH2CHSO2 CH3) has been carried out. Molecular geometry optimizations have been performed at the HF and MP2 levels of the theory. Relative energies of the stationary points have been determined by using different approac hes, including electron correlation corrections up to the third order. The IR and Raman spectra of the liquid have been measured and a vibra tional assignment is proposed. The height of the barrier to the methyl group internal rotation has been estimated. Theoretical calculations and vibrational spectra have shown that the predominant conformation o f methyl vinyl sulfone has the C=C bond eclipsed with one of the S=O b onds. Similar eclipsed forms have been found in vinyl fluoro sulfone, vinyl chloro sulfone and divinyl sulfone by ab initio HF calculations.