咪唑类化合物在乙腈溶液中负氢解离焓的理论研究

在与实验对照的基础上优化出一套计算咪唑类化合物在乙腈溶液中负氢解离焓的理论方法, 即MP2/6-311++G(d,p)//B3LYP/6-31+G(d)结合IEF-PCM溶剂模型及UA0孔穴计算法. 在此基础上, 有目的地设计了14种咪唑类负氢给体, 并计算了其在乙腈溶液中的负氢解离焓, 系统分析了影响其负氢解离焓的各种因素. 结果表明, 取代基的电子效应、体系释放负氢后的芳构化能力、咪唑环2位的苯基对前线分子轨道的贡献程度、体系电荷的分布情况及溶剂化效应等多种因素均能影响咪唑负氢给体在乙腈溶液中的负氢解离焓.

Theoretical Study on the Thermodynamic Hydricity of Imidazole-based Organic Hydrides in Acetonitrile

Theoretical thermodynamic hydricities of imidazole-based hydrides in acetonitrile were calculated by different methods.Compared with the available experimental values,it was found that the MP2/6-311++G* *//B3LYP/6-31+G* protocol with the IEF-PCM(interval equation formalism-polarized continuam model) solvent model could predict the thermodynamic hydricity with a good precision.With this method,the thermodynamic hydricities of 14 imidazole-based organic hydrides(IHs) in acetonitrile were estimated.The results show that all of the properties of substituent,the aromatization ability of IH after releasing a hydride anion,the contribution from the frontier orbital of the 2-phenyl of imidazole to the whole frontier orbital of IH and IC(the cation of IH),the natural bond orbital(NBO) charge distribution and the solvent effect have influences on the thermodynamic hydricities of imidazole-based hydrides in acetonitrile.