摘要
提出了重组能的量子化学算法 ,在用CISD/6 31G基组水平上 ,得到苯硝化反应中反应物及过渡态的结构 .并计算了各自交换电子转移反应以及交叉电子转移反应的重组能 ,同实验重组能进行了比较 .计算用了Gaus sian 94程序 .从重组能的角度分析了苯硝化反应 .结果表明 ,对于NO2 + +NO2 →NO2 +NO2 + 的自交换电子转移反应 ,重组能较大 ,结论为 :在芳烃硝化反应中 ,存在以NO2 + 为氧化剂的电子转移步骤的可能性很小 ,而从动力学的角度上 ,用NO+ 作反应的氧化剂更有可能 .
This paper presents a new theoretical model for accurately calculating reorganization energy for electron transfer reactions. The process of electron transfer is divided into six steps, and the energy change of every step can be calculated by ab initio. The structure of reactant and transition states in benzene nitride reactions is optimized on the level of CISD/6-31 G using Gaussian 94. The inner-sphere and out-sphere reorganization energy of self-exchange reactions ArH + ArH+ --> ArH+ + ArH, NO2+ + NO2 --> NO2 + NO2+ and NO+ + NO --> NO + NO+ is obtained in terms of the proposed reorganization model. The reorganization energy of cross electron transfer reaction ArH + NO + --> ArH+ + NO and NO2+ + NO --> NO2 + NO+ is also obtained. The comparison of the theoretical values and the experimental values for the reorganization energy indicates that the inner-sphere reorganization energy of reactions in NO2+ + NO2 --> NO2 + NO2+ is larger than that in NO+ + NO --> NO + NO+. While there exists little opportunity of electron transfer steps using NO2+ as an oxidizing agent, it is more possible that NO+ can be used as an oxidizing agent in the reaction of benzene because of the activation energy in proportion to the reorganization energy.
