Geometric and Electronic Structures of Hexanuclear Binary Ta/Rh Mixed Clusters

Density functional theory (DFT) was employed to investigate the geometric and electronic properties of a series of hexanuclear binary Ta/Rh clusters. The results show that most of the stable structures of the Ta/Rh mixed clusters have low symmetry and belong to the C-1 or C-s point groups while the [Ta2Rh4Cl4H8(CN)(6)](4-) clusters are highly symmetric (C-2h or C-4v). The energy gaps (Delta EH-L) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the mixed clusters are narrow and within 0.52-1.00 eV. A frontier orbital analysis of the mixed clusters clearly shows that the molecular orbitals are mainly composed of the d-orbitals of the skeleton metal atoms. When more rhodium atoms are substituted for tantalum atoms, the Ta-Rh bond has a greater influence on the stable structures of the mixed clusters and the influence of Ta-Ta bond decreases while the Rh-Rh bond has a non-bonding or anti-bonding nature.National Natural Science Foundation of China [20873107, 20373053