B2H6分子的几何构型

采用Gaussian 98程序中B3P86，BP86，B3LYP，BLYP，UHF，HF及LSDA等方法，对B_{2Ｈ6分子可能的D3d，D3h，D2d和D2h平面型状态及立体型状态 的几何构型五种情况的1重态及3重态进行了优化，得到该分子基态为1重态，它的电子状态 是^lＡg,B2H6的几何构型仍然是传统的对 称性为乙烯式的D2h结构 ，其构型如图9所示，其能量最低，是－53．5865H.a.u..两个硼原子与四个H原子所在平面 垂直于两个硼原子及另外二个H原子所在平面，二个硼原子之间的距离是R12=0 ．17542nm，B原子及H原子之间的距离是R17=0．13149nm，R13=0． 1188 4nm,它们之间的夹角分别是，∠314=∠526=121．93°，∠817=∠827=96．3°，B2Ｈ6中硼原子采用不等性的sp³轨道和另一硼原子的不等性的sp< sup>3轨道 及氢原子的1s轨道 交互重叠生成桥式三中心双电子键.三中心双电子键比双中心双电子键更为稳定，计算结果 也证实了这一点. 关键词： 2H6')" href="#">B2H6 密度泛函 几何构型 优化}

The geometrical structure of B2H6 molecule

The possible geometrical configuration of B 2H 6 molecule of D 3d ,D 3h ,D 2d and planar or stereo D 2h have long been argued about.In this work different methods of B3P86,BP86,B3LYP,BLYP,UHF,HF and LSDA in Gaussian 98 program have been used to optimize the structure of B 2H 6.Our result shwos that the ground state geometrical configuration for B 2H 6 molecules is stereo D 2h ,i.e.,the three_center two bridge hydrogen structure,in which two boron and four hydrogen atoms lie in a plane while the other two bridge hydrogen atoms lie in a plane perpendicular to it.This three_center two bridge hydrogen structure is more stable than two_center two_electron bond structure.