SiH2自由基与HNCO反应机理的理论研究

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.

Theoretical Study of the Reaction Mechanism for SiH2 Radical with HNCO

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 vibrational analysis and the Intrinsic Reaction Coordinates (IRC) calculation. The results indicate that the reaction of SiH₂ radical with HNCO has five channels, among which the reaction SiH₂＋HNCO→IM3→ TS4→IM5→TS5→IM6→SiH₂NH＋CO was the main pathway with the lowest activation energy.