论文部分内容阅读
采用密度泛函理论(DFT)中的UB3LYP方法在6-311+G(2d,2p)水平上研究了四重态和二重态的CoCH_2与H_2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,该反应在二重态和四重态上的势能面非常相似,存在两个过渡态(TS1、TS2)和两个中间体(M1、M2),反应的第一步是产生分子复合物(H_2)CoCH_2,其能量分别比反应物低66.6(四重态)和42.4 kJ/mol(二重态),第二步是H_2的加成形成HCoCH_3中间体,第三步是CH_4的消除反应.其中CH_4的消除为整个反应的速控步骤.反应在二重态和四重态势能面上存在四个交叉点,整个反应在二重态势能面和四重态势能面上交替进行.H-H键的活化在四重态上是不可逆的,反应将最终形成四重态产物,整个反应可放出能量222.9kJ/mol.
The mechanism of the reaction of CoCH_2 with H 2 at the triplet and triplet states at 6-311 + G (2d, 2p) was studied by the UB3LYP method in density functional theory (DFT). Based on the structural optimization of UB3LYP Coupling-cluster theory UCCSD (T) performs a one-point correction to each stationary point at the same level.The results show that the potential energy planes of the reaction are very similar in the doublet and quadruplet states, with two transition states (TS1 , TS2) and two intermediates (M1, M2). The first step of the reaction is to produce CoCH2, a complex of molecules with energy 66.6 (quaternary) and 42.4 kJ / mol The second step is the addition of H_2 to form the intermediate of HCoCH_3, the third step is the elimination of CH_4, in which the removal of CH_4 is the rate-controlling step of the whole reaction.The reaction has four At the intersection, the whole reaction alternates between the potential energy surface of the doublet state and the potential energy surface of the quadruplet state.The activation of the HH bond is irreversible on the quadruplet state, and the reaction will finally form the quadruplet product, and the whole reaction can release energy of 222.9kJ / mol.