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用密度泛函B3LYP方法,研究了二重态和四重态势能面自旋禁阻反应Ti+(4F,3d24s1)+C2H4→TiC2H2+(2A2)+H2的微观机理.通过自旋-轨道耦合的计算讨论了势能面交叉点和可能的自旋翻转过程.中间体IM1-4B2处,四重态和二重态间的旋-轨耦合值为59.3cm-1.自旋多重度必将发生变化,从四重态系间穿越到二重态势能面形成共价型复合物IM1-2A1,同时导致四重态势能面的势垒明显降低.到插入中间体IM2后,二重态势能面上有两条不同的反应路径,即分步和协同路径,后者在二重态势能面上得到放热产物TiC2H2+(2A2)+H2具有较低的活化势垒,4.52kcal/mol,其主反应路径为:Ti++C2H4→4IC→IM1-4B2→4,2ISC→IM1-2A1→[2TSins]→IM2-2A″→[2TSMCTS]→IM5→TiC2H2+(2A2)+H2.
The density functional theory B3LYP method was applied to study the microscopic mechanism of the spin-forbidden reaction Ti + (4F, 3d24s1) + C2H4 → TiC2H2 + (2A2) + H2 in the dipole and quadruplets. The potential energy surface cross point and the possible spin-over process.The intermediate-IM1-4B2 spin-and-rail coupling between the quartet and the dyadic state is 59.3cm-1.The spin multiplicity is bound to change from The quadruplet system traverses to the doublet potential energy surface to form the covalent complex IM1-2A1, and at the same time, the potential barrier of the quadruple state potential energy surface decreases obviously. After inserting the intermediate IM2, there are two different The reaction pathway, ie, step-by-step and cooperative route, the latter obtained the exothermic product TiC2H2 + (2A2) + H2 with a lower activation barrier of 4.52 kcal / mol on the dipole state energy surface. The main reaction path is Ti ++ C2H4 → 4IC → IM1-4B2 → 4,2ISC → IM1-2A1 → [2TSins] → IM2-2A "→ [2TSMCTS] → IM5 → TiC2H2 + (2A2) + H2.