Computational Study of the Mono- 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 characterize sulfoxy anions and dianions as large as S 2 O 8 2-, while post-HF theory ([QCISD(T)/6-31+G(2df)]//MP2/6-31+G(d)) has been used for systems as large as S 2 O 3 2- . Adiabatic and vertical ionization potentials have been computed to assess the gas-phase stability of the dianions. Three dianions (S 2 O 6 2-, S 2 O 8 2-, and SO 4 2- ·4H 2 O) are predicted to have positive vertical ionization energies. S 2 O 6 2- is predicted to have a negative (exothermic) adiabatic ionization potential; however, a large predicted geometry change between the dianion and monoanion rationalizes the measurable experimental lifetime of the dianion in the gas phase. Isotropic hyperfine coupling constants for 33 S have been calculated for the sulfoxy monoanions and compared with experiment.