硅甲基亚胺与水亲核加成反应机理的理论研究

Theoretical study on the mechanism of the nucleophilic addition reaction between silyleneimine and water

采用量子化学从头算和密度泛函方法在HF/6-31G**及B3LYP/6-31G**水平上对硅甲基亚胺与水间的亲核加成反应机理进行了理论研究.利用能量梯度法对反应途径上各驻点的几何构型进行了优化,对过渡态进行了振动分析确认.结果表明:该反应为一由两步基元过程所构成的复杂反应,两反应物首先经过一无势垒过程形成中间体复合物,该复合物经过四元环过渡态形成产物,第二步过程的活化势垒为1.67kJ·mol-1(B3LYP/6-31G**).总反应为强放热过程.

Ab initio and DFT(B3LYP) calculations using the 6-31G^(**) basis set were employed to study the mechanism of the nucleophilic addition reaction between silyleneimine and water . The structures of the reactants, intermediate complex, transition state and product were completely optimized by the Berny energy gradient technique , and the transition state was characterized by vibration frequency analysis. The reaction was found to be strongly exothermic and proceed in two steps:1) Two molecules form an intermediate complex with no energy barrier ; 2) The intermediate complex isomerizes to give the product via a four-membered ring transition state, The energy barrier is 1.67 kJ·mol^(-1) at B3LYP/6-31G^(**) level.