次甲基硅SiH与H2X(X=O,S)反应的热力学及动力学性质研究

在量子化学对SiH与H₂O和H₂S反应计算的基础上,运用统计热力学和Wigner校正的Eyring过渡态理论,计算了上述两反应在200～2000 K温度范围内的热力学函数、平衡常数、频率因子A和速率常数随温度的变化。计算结果表明,两反应在低温下具有热力学优势,而在高温下具有动力学优势。比较两反应的计算结果发现,在相同的温度下,SiH与H₂O反应比SiH与H₂S反应放热较多,但速率常数却较小。SiH与H₂O反应和前文报道的SiH与HF反应的比较表明,SiH与H₂O反应放热较少,而且在相同温度下,速率常数也较小。

Thermodynamic and Kinetic Studies on the Reactions of SiH with H2X (X=O,S)

Based on the quantum chemical study of the SiH insertion reactions with H2O and H2S, the statistical thermodynamics and Eyring transition state theory with Wigner correction are employed to compute the thermodynamic functions, equilibrium constants, A factors and rate constants of the two reactions in the temperature range 200 ～2000 K. The calculated results show that the two reactions are thermodynamically dominant at low temperature and kinetically favored at high temperature. The reaction of SiH with H2O is more exothermic than that of SiH with H2S,while the rate constant of the former reaction is lower than that of the latter at the same temperature. Comparison of the SiH + H2O reaction in the present study with the SiH + HF reaction in the previous study indicates that the reaction of SiH with H2O is less exothermic than that of SiH with HF, and the rate constant of the former is relatively smaller than that of the latter at the same temperature.