二氯硅烯与异氰酸多通道反应的理论计算

Theoretical study of the multi-channel reaction mechanism for the dichlorosilylene with isocyanic acid

采用密度泛函理论B3LYP方法研究了单重态SiCl2与HNCO的反应机理.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)确定中间体和过渡态,用QCISD(T)/6-311++G**方法计算了各个驻点的单点能.计算表明,单重态的二氯硅烯与异氰酸的反应有抽提NH、插入N-H键、插入C-O键的路径,其中HNCO+SiCl2→IM1→TS1→IM2→TS2→IM3→TS3→IM4→P1反应势垒最低,为主反应通道,产物为二氯硅甲胺(SiCl2NH)和一氧化碳(CO).

The reaction mechanism of dichlorosilylene with isocyanic acid has been investigated by B3LYP method of density function theory, and the geometries and harmonic of reactants, intermediates, transi- tion states and products have been calculated at the B3LYP/6- 311 ＋ ＋ G ＊＊ level. To obtain more precise energy result, the stationary point energies were calculated at QCISD（T）/6-311 ＋＋ G＊＊//B3LYP/6- 311 ＋＋ G ＊＊ level. Intermediates and transition states were confirmed by the results of vibration analysis and the＂ Intrinsic Reaction Coordinates （IRC） calculation. The results indicate that the reaction of singlet state dichlorosilylene with isocyanic acid has the NH abstraction channel, insert N-H and C-O channel. The pathway NCO＋SiCl2→IM1→TS1→IM2→TS2→IM3→TS3→IM4→P1 is the main one with the lowest activation energy, and the main products were SiCl2NH and CO.