苯并氧化呋咱稳定性和异构化的DFT和ab initio研究

摘要

B3LYP/6-31G(d)-DFT(Density Functional Theory)method has been employed to study benzofuroxan,o-dinitrosobenzene and the isomerization between them.The calculated results with B3LYP/6-31G(d)-DFT show:(1)the molecular total energy of benzofuroxan is lower than that of o-dinitrosobenzene;(2)the activation energy(Ea+=51.0kJ/mol)of forward reaction that benzofuroxan isomerises into o-dinitrosobenzene,is in agreement with the experimental(58.6kJ/mol)provided by reference,and the activation energy(Ea-=4.6kJ/mol)of back-ward reaction is very small.It is concluded thereby that benzofuroxan is more stable than o-dinitrosobenzene.In addition,the corresponding ab initio calculations at the level of HF/3-21G,HF/6-31G(d)and MP2/6-31G(d)//6-31G(d) were completed,and it was found that the calculated results by B3LYP-DFT method are superior to those from ab initio calculation.The calculations of harmonic vibrational frequencies with B3LYP/6-31G(d)theoretically supported that o-dinitrosobenzene is the intermediate of “self-self”tautomeric rearrangement of benzofuroxan.%运用B3LYP/6-31G(d)密度泛函理论（DFT）方法对苯并氧化呋咱、邻二亚硝基苯及其间的异构化反应进行了计算研究。结果表明，苯并氧化呋咱的分子总能量比邻二亚硝基苯的低；由苯并氧化呋咱异构为邻二亚硝基苯的正向反应活化能（Ea+=51.0kJ/mol），与文献实测值（58.6kJ/mol）较接近，而其逆向反应活化能（Ea-=4.6kJ/mol）很小，从而揭示了苯并氧化呋咱比邻二亚硝基苯更稳定·此外，进行了HF/3-21G、HF/6-31G(d)和MP2/6-31G(d)//6-31G(d)水平下相应的计算，发现B3LYP-DFT的结果较abinitio为优。谐振动频率的B3LYP/6-31G(d)计算还支持了邻二亚硝基苯为苯并氧化呋咱“自-自”互变重排反应的中间体。