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化学学报
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化学学报 ›› 1997, Vol. 55 ›› Issue (12): 1185-1190. 上一篇    下一篇

研究论文

硼烷分子中化学键性质的研究Ⅳ: B~4H~8X及B~4H~8的结构与成键特征

武海顺;许小红;张聪杰;周伟良   

  1. 山西师范大学化学系;华东师范大学化学系
  • 发布日期:1997-12-15

Studies on the nature of chemical bonding in boranesⅣ: The structure and bonding characteristics of B~4H~8X and B~4H~8

WU HAISHUN;XU XIAOHONG;ZHANG CONGJIE;ZHOU WEILIANG   

  • Published:1997-12-15

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用ab initio MP2/3-21G*方法，对四角锥型硼化物B~4H~8X(X=Li^-，Be，B^+，C^2^+，B^-，C，N^+，BeH^-，BH和CH^+)及其碎片B~4H~8的结构进行了研究。结果表明，在B~4H~8X结构中，端氢(H~t)的位置受顶点帽基X的支配。帽基原子的电负性较小和配位原子轨道的弥散程度较大时，H~t处在B~n环平面下方，与帽基反向。反之，H~t与帽基同向。桥氢(H~b)的位置总是在B~n环平面之下，与X反向。进一步研究了B~4H~8X的离解能，并进行了电子相关能校正。发现结构1和2稳定性较差，结构3～10较稳定。分子碎片B~4H~8的最稳定构型为2112结构。

关键词: 化学键, 从头计算法, 硼烷类, 成键, 构型, 结合能, 结构稳定性, 离解能, 锥形体, 结构表征

Using the ab initio MP2/3-21G* method, the structure of B~4H~8X (X=Li^-, Be, B^+, C^2^+, B^-, C, N^+, BeH^-, BH and CH^+) and their fragments of B~4H~8 have been studied. The results show that terminal hydrogen positions are controlled by the acme cap (X) in B~4H~8X molecules. When the cap atoms have smaller electronegntivity and the ligand orbitals have more diffusion, terminal hydrogen atoms can be observed below the B~n plane (against the cap). In contrast, when terminal hydrogen atoms towards the cap (X), the bridging hydrogen atoms are away from it. Further investigation on dissociation energies and correlation energies of B~4H~8X was carried out. We have observed that the structure of 1 and 2 we are unstable while the structure of 3～10 were relatively stable. In all fragments of B~4H~8, the structure with 2112 configuration is most stable.

Key words: CHEMICAL BONDS, AB INITIO CALCULATION, BORANES, BONDING, CONFIGURATION, BINDING ENERGY, STRUCTURAL STABILITY, DISSOCIATION ENERGY, CONES, STRUCTURE CHARACTERISTICS

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