气相中CuO^+活化CO中C—O键的理论计算

Theoretical Study of Activation C—O Bond of CO by CuO^+ in Gas Phase

采用密度泛函UB3LYP/6-311+G(2d)方法计算研究了CuO+在基态和激发态下与CO的反应机理,全参数优化了反应势能面上各驻点的几何构型,用频率分析方法和内禀反应坐标(IRC)方法对过渡态进行了验证,并用UB3LYP/6-311++G(3df,3pd)、单点垂直激发、自然键轨道理论(NBO)、Harvey等的方法分别进行各驻点单点能校正、单重态和三重态反应势能面交叉点CP确定、电荷转移分析、最低能量交叉点(MECP)的优化及计算.计算结果表明该反应为一步反应,反应的机理为插入消去机理;在1-3CP点构型中,Cu原子的孤对电子与O—C键的反键空轨道有着较强的稳定化能;反应能通过该构型发生了"势能曲线交叉",动力学上有效的降低了活化能,热力学上增加了反应的放热,这与实验研究结果是一致的.

The reaction mechanism between CuO＋ in ground state and excited state with CO has been studied using the density functional theory （DFT） at UB3LYP/6-311 ＋ G （2d） level, The geometries for reactants, the transition states and the products were completely optimized. All the transition states were verified by the vibrational analysis and the intrinsic reaction coordinate calculations, For each stationary point, single-point energy calculations were carried out by UB3LYP/6-311G ＋ ＋ （3df,3pd） method. The potential energy curve-crossing diagrams were investigated for state correlation between singlet and triplet spin state in the reaction of CuO＋ with CO, There is a crossing point （CP） between the singlet and the triplet potential energy surfaces, which would play a significant role in this catalytic reaction. The charge transfer has been discussed via natural bond orbit theory （NBO）. The minimum energy crossing points （ MECP）, obtained by the mathematical algorithm proposed by Harvey et al, has been also employed. The results, which are in good agreement with the results in literatures, showed that the reaction was a one-step to products and an insert-eliminate mechanism. The strong stabilization energy existed between lone pair electrons of Cu atom and anti-bond empty orbitals of the C--O bond of the 1-3 CP configuration, By the potential energy surfaces crossing, the activation energy has been effectively reduced in dynamics, the reaction heat has been obviously increased in thermodynamics, which are almost the same with experimental results.