过渡金属团簇Nbn、Con(n≤4)和NbxCoy(x＋y≤8)的芳香性

Aromaticity of Transition-Metal Clusters Nb_n,Co_n(n≤4) and Nb_xCo_y(x+y≤8)

采用杂化密度泛函(DFT)方法优化了过渡金属纯团簇Nbn,Con(n≤4)和二元铌钴团簇NbxCoy(x+y≤8)的结构,并计算了较稳定结构的NICS(核独立化学位移)值,分析这些过渡金属团簇的成键情况,讨论不同轨道对各过渡金属团簇芳香性的贡献,发现在过渡金属团簇中,除了具有s、p轨道贡献的σ、π芳香性外,很重要的地d轨道的参与而形成的#芳香性.

Abstract： The NICS （nucleus-independent chemical shift） values of steady structures of the transition-metal pure clusters Nbn,Con（n≤4） and binary transition-metal clusters NbxCoy（x＋y≤8） were calculated by using density functional theory. The electronic configurations of Nbn,Con（n≤4） and NbxCoy （x＋y ≤ 8） conformations were analyzed, and individual contributions of different orbitals to the NICS were discussed. The results indicated that s and p orbitals contributed to σ, π aromaticity of the clusters, and more importantly, d orbitals contributed to the δ aromaticity of the clusters.