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本文用CNDO量子化学方法研究了配合物(Cp_2TiAlH_3Y)_2[Y=—H(Ⅰ)、—NH_2(Ⅱ)、—OH(Ⅲ))的电子结构和化学键。研究表明:氢键结构Ti(u—H)_2AlH(u—Y)_2AlH(u—H)_2Ti是配合物中最活泼的部分。这些分子的HOMO特征主要是TiH_2;Ti—H键是带有离子成份的共价键;分子从Ⅰ、Ⅱ到Ⅲ,HOMO能量下降,Ti—H键级增加,LUMO中Ti轨道成份下降。根据文中所提出的催化机理,上述性质的变化和它们在烯烃加氢和异构化中呈现的催化活性是一致的。此外,本文还解释了分子Ⅰ双聚的原因。
In this paper, the electronic structures and chemical bonds of the complexes (Cp_2TiAlH_3Y) _2 [Y = -H (Ⅰ), - NH_2 (Ⅱ), - OH (Ⅲ)) have been studied by CNDO quantum chemistry method. The results show that the hydrogen bond structure Ti (u-H) _2AlH (u-Y) _2AlH (u-H) _2Ti is the most active part in the complex. The HOMO of these molecules is mainly TiH_2. The Ti-H bond is a covalent bond with ionic components. The energy of HOMO molecules decreases from Ⅰ, Ⅱ to Ⅲ, while the Ti-H bond order increases. According to the catalytic mechanism proposed in the text, the changes of the above properties are consistent with their catalytic activity in the hydrogenation and isomerization of olefins. In addition, this paper also explains the reason for the molecular double Ⅰ.