含氨D-A加合物的自然杂化轨道研究

Natural Hybrid Orbital Analyses on D-A Adducts of Ammonia and Various Acceptors

采用无参数Ｆｅｎｓｋｅ－Ｈａｌｌ自洽场分子轨道方法计算了氨的三类给予－接受到（Ｄ－Ａ）加合物：氢键和锂键型Ｈ３Ｎ－ＡＸ（Ａ＝Ｈ，Ｌｉ；Ｘ＝Ｆ，Ｃｌ），孤对－空位型Ｈ３Ｎ－ＢＸ３（Ｘ＝Ｈ，Ｆ，Ｃｌ，Ｂｒ）和孤对－σ型Ｈ３Ｎ－ＸＸ（Ｘ，Ｘ＝Ｆ，Ｃｌ）的电子结构，利用所得波函数对上述体系进行了自然杂化轨道分析，给出了三类加合物Ｄ－Ａ作用的定域图象。将分子价的概念推广于Ｄ－Ａ作用体系的研究。结果表明。

Parameter-free Fenske-Hall SCF MO method was used to calculate the electronic structure of three kind of D-A complexes of ammonia: H3N-AX (A = H, Li; X = F, Cl); H3N-BX3 (X = H and halogen) and H3N-XX' (X, X' = F, Cl). Based on the wave functions thus obtained, natural hybrid orbital analysis was carried out. Molecular valency was introduced and computed, which show that the valency increments of ammonia vary monotonically with the interaction intensities between acceptor (A) and donor (D) in a series of adducts. Moreover, our calculation also demonstrates that the nature of D-A interaction can be interpreted in terms of the unsaturation of molecular valency.