氧族桥原子对类立方烷簇[Mo_4X_4Cp_4′]成键特征的影响(X=O,S,Se,Te;Cp′=Cp or Pr^iCp)

Influence of the Bridging Atom Upon the Bonding Properties of the Cubane-Like Clusters [Mo_4X_4](X=O,S,Se,Te)

本文用EHMO法对(Mo_4X_4Cp′4](X=0,S,Se,Tc)四个类立方烷型簇合物的电子结构进行了计算,结果表明,桥基X从O到Te,前线区域分子轨道中桥基成分明显增加,能级普遍升高;Mo-Mo间作用有所增强;能隙ΔE(LUMO-HOMO)增大;Mulliken键级P的次序为P_(Mo-Se)>P_(Mo-S)>P_(Mo-Tc)>P_(Mo-o)>P_(Mo-Mo),说明第二过渡系元素Mo更倾向于与较重的se桥结合形成类立方烷型簇合物。

The electronic structures and bonding properties of the cubane-like clusters [Mo4X4Cp4](X =O ,S,Se,Te;Cp = Cp or Pr1Cp) have been investigated by using the EHMO method. It has been found that the change of the bridging atoms from O to Te. will give rise to a considerable increase of the components of X in the frontier orbitals,the shift of the energy levels and increase of the energy gap △E (LUMO-HOMO) as well as a slight enhancement of the Mo - Mo interactions. The sequence of Mulliken bond order is PM0-Se>PMo-S>PMo-Te>PMo-o>>PMo-Mo, which indicates that Mo atom is much easier bonding with Se atom than the others.