COMPUTATIONAL STUDY OF THE MONOANIONS AND DIANIONS OF SO2, SO3, SO4, S2O3, S2O4, S2O6, AND S2O8

DFT theory (B3LYP/6-311+G(2d)//B3LYP/6-31+G(d)) has been used to chara cterize sulfoxy anions and dianions as large as S2O82-, while post-HF theory ([QCISD(T)/6-31+G(2df)]/MP2/6-31+G(d)) has been used for system s as large as S2O32-. Adiabatic and vertical ionization potentials hav e been computed to assess the gas-phase stability of the dianions. Thr ee dianions (S2O62-, S2O82-, and SO42-. 4H(2)O) are predicted to have positive vertical ionization energies. S2O62- is predicted to have a n egative (exothermic) adiabatic ionization potential; however, a large predicted geometry change between the dianion and monoanion rationaliz es the measurable experimental lifetime of the dianion in the gas phas e. Isotropic hyperfine coupling constants for S-33 have been calculate d for the sulfoxy monoanions and compared with experiment.