The microwave and radio frequency rotation–inversion spectrum of (SO2)2

The Structures, Molecular Orbital Properties and Vibrational Spectra of the Homo- and Heterodimers of Sulphur Dioxide and Ozone. An Ab Initio Study

The structures of a number of dimers of sulphur dioxide and ozone were optimized by means of a series of ab initio calculations. The dimer species were classified as either genuine energy minima or transition states of first or higher order, and the most probable structures consistent with the experimental data were confirmed. The molecular orbitals engaged in the interactions resulting in adduct formation were identified and relations between the orbitals of the dimers of the valence isoelectronic monomer species were examined. The vibrational spectra of the most probable structures were computed and compared with those reported in the literature, particularly with spectra observed in cryogenic matrices. The calculations were extended to predict the properties of a number of possible heterodimers formed between sulphur dioxide and ozone.

Complexes containing CO2and SO2. Mixed dimers, trimers and tetramers

Two stable minima for the 1 : 1 heterodimer of CO₂ : SO₂, both bound by about 2 kcal mol⁻¹. Binding is dominated by charge transfer from O lone pairs of SO₂to CO π* antibonding orbitals.