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利用群论的方法及定域键的观点可以把轨道对称守恒原理表述为键对称守恒规律。即对于一个化学反应,如果生成键的对称性和断裂键的对称性相同,则反应是对称允许的;反之,反应是对称禁阻的。由于在化学反应中,常伴随有孤对电子变成成键电子或成键电子变成孤对电子,所以在研究化学反应时,除考虑到生成键和断裂的对称性外还必须研究孤对电子的变化。这样,借助“化学键”和“孤对电子”的概念来研究化学反应的机理,比用离域的“正则分子轨道”更为直观和简便。
The theory of conservation of orbital symmetry can be expressed as the law of conservation of symmetry using the method of group theory and the viewpoint of localized bond. That is, for a chemical reaction, the reaction is symmetrically allowed if the symmetry of the generated bond is the same as the symmetry of the broken bond; conversely, the reaction is symmetrically forbidden. Due to the chemical reaction, often accompanied by a lone pair of electrons into a bonding electron or bonding electron into a lone pair of electrons, so in the study of chemical reactions, in addition to taking into account the symmetry of bond formation and fracture must also study the lone pair Electronic changes. In this way, it is more intuitive and convenient to study the chemical reaction mechanism by using the concept of “chemical bonds” and “lone pair electrons” than to use the “regular molecular orbitals” of delocalization.