Theoretical study on the Cl + CH3S(O)CH3 reaction

By means of direct dynamics methods theoretical investigations are carried out on the multiple-channel reaction system Cl + CH3S(O)CH3. The optimized geometries, frequencies and minimum energy path (MEP) are all obtained at the BH&H-LYP/6-311G(2d,2p) level, and energetic information is further refined by the MC-QCISD (single-point) theory. The rate constants for two main reaction channels, to yield CH3S(O)CH2 + HCl and to yield CH3S(O)Cl + CH3, are calculated by canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) contributions over the wide temperature region 200-2000 K. The theoretical overall rate constants and the branching ratio are in good agreement with the available experimental data; and the three-parameter formula k = 1.32 × 10−16T2.18exp(−48.12/T) cm3 molecule−1 s−1 over the temperature region 200-2000 K is given. For the title reaction, CH3S(O)CH2 + HCl is the major product, and CH3S(O)Cl + CH3 is a minor product over the whole temperature region.