硼烷缺电子多中心桥键的H-F力研究

Hellmann-Feynman静电力表现了分子中电荷分布及对各原子核的作用。H-F力的方向性可描述电子电荷的数量和位置,具有定量、形象和直观的特点,已在弯键的研究中显示出来。这一方法尚可用于多中心缺电子桥键的研究。 1 理论与方法 按LCAO-MO理论对H-F力进行分解,除有重叠力、极化力和屏蔽力外,还有一

A Study of H-F Force for Multicentre Bridge Bond in Electronic Deficient Molecule Boranes

The bridge force term in partition the H-F force is defined, which means the force acting on a nucleus A coming from the overlap of electronic charge density, between atoms B and C. The bridge forces in molecules B2H8 and C2H4 etc. are computed by means of quantum chemical ab initio method. The results show that the effect of bridge force in normal molecules (e.g.C,H4) can be neglected, but it may play a important role in multicentre bridge bond of electronic deficient molecules (e.g.B2H6). The equivalent point charge of the overlap force and its position in molecule B2H6 are calculated. According to these data a electronic charge distribution diagram of molecule B2H6 is drawn, which may clearly represent the character of chemical bond in a molecule.