X_2H_6(X=ⅢA族)化学键的量子化学研究(英文)  

Quantum Chemical Study on the Bondings in X_2H_6(X=ⅢA Group)

作　　者：张金生[1] 

机构地区：[1]贵州师范大学化学与材料科学学院,贵阳550001

出　　处：《西南大学学报（自然科学版）》2011年第11期81-89,共9页Journal of Southwest University(Natural Science Edition)

基　　金：贵州省科学技术基金资助项目(黔科合J字[2009]2241号);贵州师范大学博士基金资助项目

摘　　要：在CCSD/6-311++G(3df,3pd)的计算水平对X2H6(X=ⅢA族)的结合能和化学键进行了理论研究.结果表明,X2H6都具有与B2H6相似的几何结构,分子中存在两个共平面的三中心两电子氢桥键τM—H'—M.考虑了XH3单体结合成二聚体时的变形能和基组重叠误差(BSSE),B2H6,Al2H6,Ga2H6,In2H6和Tl2H6的结合能分别为167.7,150.6,106.5,97.4和79.3kJ/mol.桥氢原子(H')具有比σ-氢原子(H)更负的原子极化张量电荷.X—H的键级为0.961.00,以共价性为主.而X—H的键级为0.400.47,以离子性为主(B2H6除外).在B2H6,Al2H6,Ga2H6,In2H6和Tl2H6中,X—H共价性百分比分别是96.3%,62.3%,70.2%,59.0%和68.6%,而X—H离子性百分比分别是47.9%,68.1%,62.9%,71.5%和69.4%.B2H6的主要共振结构是H+[B2H5]-(占37.22%),而其他二聚体的主要共振结构是XH3.XH3(占61.77%-69.75%).The binding energies and bindings of X2H6（X=B,Al,Ga,In and Tl） are theoretically studied at the CCSD/6-311＋＋G（3df,3pd） calculation level.The result reveals that X2H6 adopts a D2h structure containing four terminals and two bridging-hydrogen atoms and contains two coplanar three-center two-electron（3-c 2-e） tau bonds,τX—H＇—X.Taking into account both the deformation energy and the basis set superposition error（BSSE） of the monomer,B2H6,Al2H6,Ga2H6,In2H6 and Tl2H6 have binding energies of 167.7,150.6,106.5,97.4 and 79.3 kJ/mol,respectively.Compared with the normal σ-hydrogen atoms（H）,the bridged-hydrogen atoms（H＇） show more negative atomic polar tensors（APT） charges.The bond orders of X—H and X—H＇ are in the ranges of 0.96~1.00 and 0.40~0.47,respectively.Moreover,covalent contribution is dominant in X—H bond while ionic contribution is favored in X—H＇ bond（except B2H6）.In B2H6,Al2H6,Ga2H6,In2H6 and Tl2H6,the covalence ratios of X—H are 96.3,62.3,70.2,59.0 and 68.6%,respectively,while the ionic contributions of X—H＇ are 47.9,68.1,62.9,71.5 and 69.4%,respectively.The most dominant resonance structure of B2H6 is H＋-,which accounts for 37.22% of the total,whereas the most dominant resonance structure for other X2H6 are XH3·XH3,which accounts for 61.77~69.75% of the total.

关 键 词：三中心两电子氢桥键 单双激发耦合簇线性响应理论 基组重叠误差(BSSE) 共价性成分 自然共振理论 

分 类 号：O643.12[理学—物理化学]