Infrared spectra and ab initio calculations of matrix isolated dimethyl sulfone and its water complex

The infrared spectrum of (CH₃)₂SO₂ (dimethyl sulfone) trapped in several rare gas matrices is reported. Results are compared to previous gas phase and solid state spectra. In water-containing matrices, bands attributed to the ((CH₃)₂SO₂)*(H₂O) molecular complex are identified. Spectral results are discussed with reference to the bonding scheme suggested by theoretical ab initio calculations. The similarities to the previously recorded (H₂SO₄)*(H₂O) mode frequencies shed light on the bonding scheme of both. The complex formation between H₂O and dimethyl sulfone was studied by ab initio B3LYP computations using the aug-cc-pVTZ basis sets. The calculations show the existence of a stable 1∶1 complex of C_s symmetry, Δ_fH = −21 kJ mol⁻¹, with a single O⋯H bond of one water hydrogen bonded to one oxygen of the sulfone.