H-Bonded CH 3 SO/H 2 SO 4 /H 2 O Complexes: Quantum Chemical Study

Abstract

The structural, electronic, and spectroscopic properties of complexes between methyl sulfinyl radical, sulfuric acid and water molecules have been studied by density functional theory and ab initio methods. The hydrogen bond interactions between the CH₃SO radical, H₂SO₄ and H₂O molecules have been characterized. Calculations predict relative large binding energies of the complexes being 12.2 kcal mol^-1 for the most stable CH₃SO-H₂SO₄ complex, 19.1 kcal mol^-1 for CH₃SO-H₂SO₄-H₂O complex and 28.8 kcal mol^-1 for CH₃SO-H₂SO₄-2H₂O complex at CBS-QB3 level of theory. The relatively high stabilization of the complexes is likely to have significant effects on the overall processes that lead to formation of new particles in the atmosphere. Infrared spectroscopy is suggested as a potential useful tool for detection of these complexes either in the laboratory experiments or in the atmospheric observations. The electronic spectra of the complexes have been examined and their photochemical spectral features are discussed. The hydrated CH₃SO-H₂SO₄ complexes can be expected to undergo photolysis in the sunlight.