(dmpe)_2HCrBH_4、(dmpe)_2HCrAIH_4和[(dmpe)_2HCrAIH_4]_2的电子结构  

THE ELECTRONIC STRUCTURES OF (DMPE)_2 HECRBH_4 (DMPE)_2 HERALH_4 AND [(DMPE)_2HERALH_4]_2

作　　者：蔡国强[1] 吴念慈 董南 

机构地区：[1]浙大化学系,杭州310027 [2]杭大化学系,杭州310028

出　　处：《化学研究与应用》1990年第4期47-52,共6页Chemical Research and Application

摘　　要：本文用CNDO/2方法研究了(dmpe)_2H_tCrBH_4(Ⅰ)、(dmpe)_2H_tCrAlH_4(Ⅱ)和[(dmpe)_2H_tCrAlH_4]_2(Ⅲ)(dmpe=(CH_3)_2PCH_2CH_2P(CH_3)_2,在计算时,我们用二个PH_3代替一个(dmpe)的电子结构。结果表明:(1)在(Ⅱ)的6b_1(HOMO),7a_1占据轨道中,Cr3d轨道与2H_b1S轨道(H_b为桥氢原子)对称性不匹配,相互排斥,而在(Ⅰ)中这种排斥有所减弱;Cr(u-H_b)_2Al骨架较Cr(u-H_b)_2B能量高而不稳定。(2)在(Ⅲ)的电子结构中Cr3d与2H_b1S之间排斥大为减弱,Cr(u-H_b)_2Al稳定性提高;新形成的AL(u-H)_2AL能量较低;在较高占据轨道中H_t和H_b成份多,活泼性强,这可能是H_t和H_b易交换的主要原因。三个化合物在电子结构上的差异较合理解释了实验现象。A theoretical study on the electuonic structures of (dmpe)_2HtCrBH_4(Ⅰ), (dmpe)_2HtCrlH_4(Ⅱ) and [(dmpe)_2HtCrAlH_4l_2(Ⅲ) dmpe=(CH_3)_2PCH_2CH_2P(CH_3)_2, inwhich we have used two H_3 instead of one dmpe in calculations has been carried out by cndol_2 method.The results showed: (1) in occupied Mo, 6b_1 (HOMO) and 7a_1 in(Ⅱ), Cr 3d orbital repulses with Hb ls orbital (Hb is bridge judrogen atom), bnt in (Ⅰ), this repulsion is weaken; Cr(u-Hb)_2B is more stable and in lower energy than Cr(u-Hb)_2Al. (2) In the electronic structure of(Ⅲ, the repulsion between Cr 3d and H ls is weaken largely; Al(u-Hb)_2Al is in low energy. Ht和Hb are active for theirr large contribution to higher occupied Mo and it may be the reason of easy cxchangc nctwccn Ht and Hb in solution. The differences in their electronic structurc are in agreement with experiment result.

关 键 词：铬的硼氢化合物 铬的铝氢化合物 CNDO/2 电子结构 

分 类 号：O6[理学—化学]