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化学活性与分子结构的相互关系,是每一个化学工作者十分感兴趣的问题,又是一个十分复杂的问题。七十年代起,R.Hoffmnn等采用的碎片分子轨道近似方法以及“同瓣相似”的概念,抓住影响化学活性的主要因素,进一步发展了应用分子轨道对称守恒原理来探索化学反应的规律。碎片分子轨道近似的基本思想,是把分子视为由几个碎片组成,应用量子化学的计算结果来考察“碎片”的前线轨道。从而揭示化学活性与结构之间的内在联系。如果两个碎片的前线轨道的数目、对称性、空间取向以及能级都相似——不是相同,而是相似,
The relationship between chemical activity and molecular structure is a matter of great interest to every chemist and is a very complex issue. Since seventies, R. Hoffmnn et al. Used the method of fragment molecular orbit approximation and the concept of “homologous similarity” to seize the main factors that affect the chemical activity and further develop the rule of using chemical orbital symmetry conservation principle to explore chemical reactions. The basic idea of fragment molecular orbit approximation is to consider the molecule as consisting of several fragments and to apply the quantum chemical calculations to investigate the “fragment” frontier orbit. Thereby revealing the chemical activity and the inherent relationship between the structure. If the number of frontier orbits, symmetry, spatial orientation, and energy levels of two fragments are similar - not the same, but similar,