Structural Evolution and Electronic Properties of V₂Si_n^-/0 (n=7-14) Clusters: Anion Photoelectron Spectroscopy and Theoretical Calculations

A systematic study of the structures and electronic properties of V-2-doped silicon clusters, V2Sin-/0 (n = 7-14), was carried out by anion photoelectron spectroscopic experiments combined with theoretical calculations. According to the experimental spectra of V2Sin- (n = 7-14) clusters, the V2Si12 (-) cluster has the highest vertical detachment energy (VDE) of 3.66 eV, while V2Si7- and V2Si14- clusters have lower VDEs of 2.81 and 2.84 eV, respectively. The most stable structure searches find that two V atoms in the V2Sin- clusters with size n = 7 and 8 are located at the surface, while V2Sin- clusters with n = 9 prefer cage-like structures. Based on the analysis of the structural evolution of V2Sin- (n = 9-14) clusters, it can be clearly seen how the antihexagonal prism with one V encapsulated in the cage is gradually built from n = 9 to 12 and further developed from n = 12 to 14 with the extra silicon atoms located at the surface of the Si-12 cage. The molecular orbital and the atoms in molecule analysis of the V2Sin- (n = 7-14) anions demonstrate that the strong V-V bond and the delocalized interaction between the V-2 moiety and the Sin ligand play a significant role in stabilizing the cluster structures. A strong linear correlation has been found between the Wiberg bond order of the V-V bond and the electron density at the V-V bond critical points.