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用从头算自洽场方法在3-21G水平上研究了丙酮在n→π~＊激发单态(S_1(n,π~＊))势能表面上的光解反应。优化出的反应物S_1(n,π~＊)态的丙酮分子的几何构型偏离C_(2v)对称性的基态构型,即O原子弯出3个C原子的平面39.3°,且甲基的旋转角度为50.5°。该结论与实验的结果取得了一致。该反应途经一个C_1对称性的过渡态而分解为一个n→π~＊激发态的乙酰基和一个基态的甲基。计算的反应活化位垒和垂直激发能分别为208.19和290.25kJ·mol~(-1)。该值与光解离的实验条件相吻合。
The photolysis of acetone over the n → π ~ * excited singlet (S 1 (n, π ~ *)) potential energy surface was investigated at the 3-21G level using ab initio method. The optimized geometries of the acetone molecules in the S_1 (n, π ~ *) state deviate from the C_2v symmetry ground state configuration, that is, the 39.3 ° O atom is bent out of the plane of three C atoms and the methyl The rotation angle is 50.5 °. This conclusion is consistent with the experimental results. The reaction proceeds via a C_1 symmetric transition state into an acetyl group of n → π ~ * excited states and a ground state methyl group. The calculated reaction activation barriers and vertical excitation energies were 208.19 and 290.25 kJ · mol -1, respectively. This value is in agreement with the experimental conditions for photodissociation.