Strongly hydrogen-bonded molecular complexes studied by matrix isolation vibrational spectroscopy. Part 4.—Dimethyl sulphoxide–hydrogen halide complexes

Abstract

Infrared spectra are reported of strongly hydrogen-bonded complexes between dimethyl sulphoxide or [²H₆]dimethyl sulphoxide and hydrogen chloride or hydrogen bromide in argon and nitrogen matrices. Although there are differences between the spectra of the complexes in the two matrices, the extent of proton transfer does not change markedly from an argon matrix to a nitrogen matrix (unlike the amine–hydrogen halide complexes). There is substantial mixing of the O⋯H⋯Cl stretching and bending modes with vibrational modes of the dimethyl sulphoxide molecule. In the hydrogen bromide complex, the proton is more or less equally shared between the oxygen and bromine atoms; the extent of proton transfer is smaller in the hydrogen chloride complex.