HSS和HS反应机理的理论研究

Theoretical Study on the Reaction Mechanism of HSS and HS

在B3LYP/6-311＋G（3df,2p）水平上对HSS和SH反应过程中所有物种进行了构型优化和频率计算,用高水平G2M（CC5）方法对各个物种做了单点能校正,获得了反应的势能剖面。结果表明,HSS与SH反应体系中主要存在2条反应通道,其中生成P1（H2S＋S2）的通道为优势通道,此通道包含2条路径具有相同的决速步,对应表观活化能为8.15 k J·mol^-1。另一条为生成P2（H2＋S3）的过程,该反应需克服18.37 k J·mol^-1的表观活化能。利用经典过渡态理论,计算了上述2条通道主路径决速步在200~2000 K温度变化范围内速率常数,此结果可用于后续实验研究。

The equilibrium geometries and frequencies of all the stationary point for the reaction of HSS with HS are calculated using B3 LYP /6- 311 ＋ G（ 3df,2p） method. Single point energies of all the species are computed at the G2M（ CC5） level,and single potential energy surface is constructed. Three channels（ four pathways） are found for the HSS ＋ SH reaction. The result suggested that the formation of P1（ H2 S ＋ S2） is dominated channel including two pathways,which had the same rate- determining step with the apparent activation energy of 8. 15 k J·mol- 1. In addition,the product P2（ H2＋ S3） is also confirmed with the apparent activation energy of 18. 37 k J·mol- 1. The rate constants are evaluated by means of the classical transition state theory over the temperature range of 200 ~ 2000 K.The result indicated the rate constant increases with the temperature range from 200 to 2000 K.