Theoretical studies on SOx (x = 1-3) formation in the reaction of CH3SO radical with O3

The reaction of CH3SO radical with O3 has been studied at MP2/6-311++G (2df, p) level. Geometries of the reactants, transition states (TS) and products have been optimized and the transition states are found for the first time. The breakage and formation of the chemical bonds in the reaction have been discussed by the topological analysis of electronic density. The following conclusions were obtained: Because the reaction has relative high energy barrier, the CH3SO can be oxidized by O3 at high temperature. The major oxidized products, SO2 and SO3, are the precursor substance of acid rain. Furthermore, OSOO → SO3 (D3h) reaction consists of two elementary reaction, the topological analysis of electron density results show that the ring transitional structure region exists not only in OSOO → SO3 (Cs) process but also in SO3 (Cs) → SO3 (D3h) process. It is the first time we found a ring transitional structure exists in two elementary reactions. And there are two kinds of S-O bond characters in different SO3 isomers.