H-Bonded CH3SO/H2SO4/H2O Complexes: A Quantum Chemical Study

The structural, electronic, and spectroscopic properties of complexes of the methyl sulfinyl radical, sulphuric acid and water molecules have been studied by density functional theory and ab initio methods. The hydrogen bond interactions between the CH(3)SO radical, H(2)SO(4) and H(2)O molecules have been characterised. The calculations predict relatively large binding energies for the complexes of 12.2 kcal mol-1 for the most stable CH(3)SO-H(2)SO(4) complex, 19.1 kcal mol-1 for CH3SO-H(2)SO(4)-H(2)O complex and 28.8 kcal mol-1 for CH(3)SO-H(2)SO(4)-2H(2)O complex at the CBS-QB3 level of theory. The relatively high stabilisation of the complexes is likely to have significant effects on the overall processes that lead to the formation of new-particles in the atmosphere. Infrared spectroscopy is suggested to be a potentially useful tool for the detection of these complexes either in laboratory experiments or in atmospheric observations. The electronic spectra of the complexes have been examined, and their photochemical spectral features are discussed. The hydrated CH(3)SO-H(2)SO(4) complexes can be expected to undergo photolysis in sunlight.