SiH_2自由基与HNCO反应机理的理论研究  

Theoretical Study of the Reaction Mechanism for SiH_2 Radical with HNCO

作　　者：耿志远[1] 韩彦霞[1] 王永成[1] 梁俊玺[1] 闫盆吉[1] 姚琨[1] 贾宝丽[1] 

机构地区：[1]西北师范大学化学化工学院甘肃省高分子重点实验室,兰州730070

出　　处：《化学学报》2007年第24期2839-2846,共8页Acta Chimica Sinica

摘　　要：采用密度泛函理论B3LYP方法研究了SiH2自由基与HNCO的反应机理,并在B3LYP/6-311++G**水平上对反应物、中间体、过渡态进行了全几何参数优化,通过频率分析和内禀反应坐标(IRC)确定了中间体和过渡态.为了得到更精确的能量值,又用QCISD(T)/6-311++G**方法计算了在B3LYP/6-311++G**水平优化后的各个驻点的相对能量.计算结果表明SiH2自由基与HNCO的反应有五条反应通道,其中顺式反应通道SiH2+HNCO→IM3→TS4→IM5→TS5→IM6→SiH2NH+CO反应能垒最低,为主反应通道.The reaction mechanism of SiH2 radical with HNCO has been investigated by a B3LYP method of density functional theory, while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311＋ ＋G＊＊ level. To obtain more precise energy result, stationary point energies were calculated at a QCISD （T）/6-311＋＋G＊＊// B3LYP/6-311 ＋ ＋G＊＊ level. The intermediates and transition states were confirmed by the results of vibra- tional analysis and the Intrinsic Reaction Coordinates （IRC） calculation. The results indicate that the reaction of Sill2 radical with HNCO has five channels, among which the reaction Sill2 ＋ HNCO→IM3→ TS4→IM5→TS5→IM6→SiH2NH＋CO was the main pathway with the lowest activation energy.

关 键 词：SiH2自由基 HNCO 反应机理 活化能 过渡态 

分 类 号：O643.12[理学—物理化学]