A theoretical study on the strength of two-center three-electron bonds in the NO 3 radical adducts of reduced sulfur molecules, H 2S, CH 3SH, CH 3SCH 3, and CH 3SSCH 3

Abstract

It is widely known that addition of a radical species to the sulfur atom of a reduced sulfur molecule results in formation of a two-center three-electron (2c-3e) bond, but relatively few investigations have been reported for the 2c-3e bond between the NO 3 radical and a sulfur molecule. This article presents results of gas-phase DFT and ab initio investigations on the 2c-3e type adducts of the NO 3 radical with reduced sulfur molecules. By using correlation consistent basis sets, geometry optimizations at the MP2 and BH&HLYP levels and single-point energy evaluations at the CCSD(T) level were carried out. Our estimates for the dissociation enthalpies (Δ H (298 K)) of the 2c-3e S–O bonds in the NO 3 radical adducts of the CH 3SH, CH 3SCH 3, and CH 3SSCH 3 molecules are 7∼10, 15∼16, and 10∼12 kcal/mol, respectively, but our calculations suggest that the H 2S molecule will not actually form a 2c-3e adduct with the NO 3 radical.