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采用从头计算HF,MP2方法和密度泛函理论,对Au(II)系列化合物[Au(CH2)2PH2]2X2(X=F,Cl,Br,I)的几何结构、电子结构和振动频率进行了研究.研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键.Au—Au,Au—X键强烈的电子相关作用使HF方法不适于该体系的研究,BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长,而MP2方法和局域的密度泛函方法则给出了合理的结构参数.局域密度泛函方法计算得到的Au—Au键和Au—X键振动频率也与实验数据符合较好.还运用含时密度泛函理论计算了[Au(CH2)2PH2]2X2的电子激发能,对分子在紫外-可见光谱范围内的电子跃迁进行了分析,考察了卤素配体对激发能的影响,并结合分子轨道能级的变化对此给予了解释.
The geometries, electronic structures and vibrational frequencies of the Au (II) series of compounds [Au (CH2) 2PH2] 2X2 (X = F, Cl, Br, I) were studied by ab initio calculations of HF, MP2 and density functional theory The results show that the 5d and 6s electrons of Au participate in the bonding between Au-Au and Au-X. The strong electron-related effect of Au-Au and Au-X bonds makes the HF method unsuitable for the study of this system. BP86 and B3LYP The two functionalities give larger Au-Au and Au-X bond lengths, while the MP2 method and the local density functional method give reasonable structural parameters. The Au- The vibrational frequencies of Au bond and Au-X bond are in good agreement with the experimental data. The electronic excitation energy of [Au (CH2) 2PH2] 2X2 was also calculated using the time-dependent density functional theory The electronic transition has been analyzed to investigate the effect of halogen ligands on the excitation energy, which is explained by the change of molecular orbital energy level.