부산대학교 도서관

The multiple-channel reactions Br + CH3SCH3 → products are investigated by direct dynamics method. The optimized geometries, frequencies, and minimum energy path are all obtained at the MP2/6-31+G(d,p) level, and energetic information is further refined by the G3(MP2) (single-point) theory. The rate constants for every reaction channels, Br + CH3SCH3 → CH3SCH2 + HBr (R1), Br + CH3SCH3 → CH3SBr + CH3 (R2), and Br + CH3SCH3 →CH3S + CH3Br (R3), are calculated by canonical variational transition state theory with small-curvature tunneling correction over the temperature range 200–3000 K. The total rate constants are in good agreement with the available experimental data, and the two-parameter expression k(T) = 2.68 × 10-12 exp(-1235.24/T) cm3/(molecule s) over the temperature range 200–3000 K is given. Our calculations indicate that hydrogen abstraction channel is the major channel due to the smallest barrier height among three channels considered, and the other two channels to yield CH3SBr + CH3 and CH3S + CH3Br are minor channels over the whole temperature range. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007 [ABSTRACT FROM AUTHOR]