Structures and Vibrational Spectra of SOnp– Sulfur Oxides, MSOn– Anions, and MSOn, M2SOn Salts in the Gas phase (n = 1–3; p = 0–2; M = Li, Na, K). A Density Functional Theory Study

This theoretical study focuses on geometries, vibrational spectra, charge distributions, electron affinities, and reaction energies for SOnp– anions and alkali salts MSOn–, M1,2SOn in the gas phase (n = 1–3; p = 0–2; M = Li–K). Most of our data for compounds with the S oxidation states 0, 2, and 4 are new in the literature. The bulk of the results are obtained at the B3PW91 level, with CCSD(T)=FC calculations carried out for relative energy calibrations; the 6-311+G(3df) basis set is used throughout. The formation of contact ion pairs is prevalent; they are of type: (i) M+(SOn–) for the π-radicals MSO, MSO2, MSO3 of doublet multiplicity; (ii) (M+)2(SOn2–) for M2SO, M2SO2, M2SO3 in their singlet ground states; and (iii) M(ns)(SOn–) for the radicals MSO–, MSO2–, MSO3– in their triplet states. When isolated in matrices, M2SO and M2SO2 will facilitate the spectroscopic study of the little known SO2– and SO22– ions. Divalent M2SOn salts, due to their large dipole moments, should be highly soluble in polar solv...