二氯硅烯与异硫氰酸反应的理论计算研究

A Theoretical Study of the Multi-channel Reaction Mechanism for the Dichlorosilylene with Isothiocyanic Acid

采用密度泛函理论B3LYP方法研究了二氯硅烯(Si Cl2)自由基和异硫氰酸(HNCS)的反应机理。在6-311++G**基组水平上对反应物、中间体和过渡态进行了全几何参数优化,并通过频率分析和内禀反应坐标(IRC)确定各反应通道中的中间体和过渡态,再用QCISD(T)方法计算了各个驻点的单点能。计算结果表明:单重态的Si Cl2与HNCS有插入N-H键和C-N键的反应路径,其中经由三元环插入C-N键的反应通道反应势垒最低,是主反应通道。该反应主产物为Si Cl2NHCS。

The reaction mechanism of dichlorosilylene with isothiocyanic acid is investigated through B3LYP method of density function theory,and the geometries and harmonic of reactants,intermediates, transition states and products is calculated at the B3LYP/6-311++G**level.To obtain more precise energy result,the stationary point energies are calculated at QCISD( T)/6-311++G**//B3LYP /6-311 ++G**level.Intermediates and transition states are 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 isothiocyanic acid has the insertion N-H and C-N channel,respectively.The pathway HNCS+SiCl2→IM2→TS2→IM3→TS3→P1 is the main one with the lowest activation energy, and the main products are SiCl2 NHCS.