甲硅硫醛(H2SiS)脱氢反应的反应路径解析

本文用内禀反应坐标(IRC)方法讨论了甲硅硫醛分子的脱氢反应机理. 在RHF/4-31G基组上对此反应做了量子化学从头计算和反应路径解析, 得到H_2SiS的平衡几何、过渡态结构、反应势能曲线、活化能, 反应热以及沿反应坐标一些物理量的变化, 并对平衡几何和过渡态做了振动分析. 同时, 计算了反应的频率因子A和在500 K时的活化熵△S≠。

Eraction Ergodography for Dehydrogenation of Silathione

The reaction mechanism for dehydrogenation of silathione H_2SiS was studied by means of intrinsic reaction coordinate (IRC) method. The reaction ergodography was analyzed by ab initio MO calculations using RHF/4-31G basis set. The equilibrium structure of H_2SiS which has C_(2υ). symmetry was optimized.The bond lengths of Si-S and Si-H are 0.2018 nm and 0.1484 nm, respectively. The bond angle of HSiS is 125.3°. The transition state was also located which has C_3 symmetry. The bondlengths of Si-S, Si-H_1 and Si-H_2 are 0.2045 nm, 0.1860 nm and 0.1522 nm, respectively. The bond angles of H_1SiS and H_2SiS are 105.0° and 147.4°, respectively. The activation energy was calculated to be 396.4 kJ·mol~(-1) and the reaction heat is 210.0 kJ·mol~(-1). The change of some physical properties along IRC were presented. At the same time, the vibrational analyses of the reactant and the transition state have also been done. At last, the frequency factor A of the reacton and the entropy of activation at 500 K were calculated with the application of RRKM theory. The results of H_2SiS were compared with its carbon analogy; thioformaldehyde CH_2S.