AB-INITIO STUDIES OF THE THERMOCHEMISTRY OF THE BISULFITE AND THE SULFONATE IONS AND RELATED-COMPOUNDS

High-level ab initio calculations, with and without solvent effects, w ere completed to resolve the contradictory experimental and theoretica l results on the relative stabilities of the bisulfite ion, HOSO2-, an d its tautomer, the sulfonate ion, HSO3-. Calculations at the G2 level reveal that the sulfonate anion is more stable in both the gas and aq ueous phases by approximately 4-5 kcal/mol. Contradictory results were obtained if inadequate polarization functions were used on the sulfur atom. The gas-phase heat of formation, Delta H-f 298(o), for the bisu lfite and sulfonate ions are respectively -165 and -169 kcal/mol. The first value compares favorably to the gas-phase experimental result eq ual to -165.6 +/- 2.5 kcal/mol for the bisulfite anion.