有机配体Schiff碱4-(2-羟基苯基)-亚氨基-戊-2-酮的从头算研究

Ab Initio Research of Organic Ligand Shiff Base 4-[(2-Hydroxyphenyl)Imino]-2-Pentanone

本文通过从头算HF／6-31G（d）方法，对Schiff碱4-(2-羟基苯基）- 亚氨基- 戊- 2 - 酮进行了理论研究，提供了该化合物两种互变异构体的几何构型参数、电子结构、IR光谱性质、偶极矩数据，并借助热、动力学手段，分析了两种互变异构体的异构平衡过程。计算结果表明：（1）从几何构型、电子结构和相对能量的角度考虑，由于较强的分子内氢键作用和较大的共轭体系，亚胺烯醇式更力稳定。（2）从分子极性的角度考虑，烯胺酮式具有较大的偶极矩，其较强的分子间作用力有利于形成晶体，因而烯胺酮式以晶体的形式存在。（3）由烯胺酮式向亚胺烯醇式转化的互变异构反应是热力学自发反应，但受到较大活化能的控制，是一个动力学稳定体系。分析了极性溶剂存在将有利于反应发生且标题化合物以亚胺烯醇式存在于极性溶剂中的原因。以上结论均与实验研究结果相符。

Based on the experiments, using ab initio HF/6-31G(d) method, Schiff base 4[ (2-hydroxyphenyl) imino] -2-pentanone was studied theoretically. The geometry, electron structure, IR spectroscopic property and dipole moment were calculated. The isomerization equilibrium was also analyzed with thermodynamics and kinetics. The result shows: (l) As for the geometry and electron, imine-enol mode is more stable than enamine-ketone mode because of stronger hydrogen bond and lager conjugate system. (2) As for the polarity of the molecular, enamine-ketone mode has stronger dipole moment, so it has stronger intermolecular force and can exist in crystal easily. (3) The isomerization equilibrium that enamine-ketone mode changed into imine-enol is supported by thermodynamics, but because of big activation energy, the isomerization equilibrium is a kinetic stable system. Analysis is given to the reason why the existence of polarity solvent can make the isomerization equilibrium process. The above results are all in accord with the experiments.