Fe(5D/3D)+CH2(1A1)→FeC+H2的理论研究

采用密度泛函理论(DFT)中的UB3LYP方法在6-311 G(2d,2p)水平上研究了五重态和三重态的Fe与单重态CH2反应的机理,在UB3LYP结构优化的基础上用耦合簇理论方法UCCSD(T)在相同水平下对各驻点进行了单点能校正.结果表明,该反应在三重态和五重态上的势能面非常相似,都经过两个过渡态(TS1、TS2)和三个中间体(FeCH2、HFeCH、H2FeC),五重态和三重态势能面在形成中间体FeCH2前发生交叉,整个反应沿三重态路径进行,最后得到三重态的FeC和H2.该反应是一个四步反应,其中由HFeCH到H2FeC的反应步骤为整个反应的速率控制步骤,反应的活化能为176.3 kJ/mol.

Theoretical study on the reaction of Fe(5D/3D)+CH2(1A1)→FeC+H2

The mechanism of reaction between CH_2(singlet state) and Fe(quintet and triplet states) was discussed in detail.All the structures of intermediate and transition states were optimized at UB3LYP/6-311 G(2d,2p) level of theory.Based on the optimized structures,single point energy correction was performed at UCCSD(T)/6-311 G(2d,2p) level of theory.The results indicated that the reaction in triplet and quintet states had a very similar energy surface.There were two transition states(TS1,TS2) and three intermediate states(FeCH_2,HFeCH,and H_2FeC) in both reaction energy surfaces.The energy surfaces of quintet and triplet states had an intersection before the formation of FeCH_2 intermediate,the reaction processes along with triplet state and the products were triplet FeC and H_2.The reaction was composed of four steps and the speed control step was the formation of H_2FeC from HfeCH,the activation energy was 176.3?kJ/mol.