A photoelectron spectroscopy and density functional study of di-tantalum boride clusters: Ta2Bx- (x=2-5)

The structural and electronic properties for di-tantalum boride clusters Ta2Bx- (x = 2-5) were investigated using photoelectron spectroscopy and density functional calculations. The photoelectron spectra for Ta2Bx- (x = 2-5) are obtained at several photon energies with rich spectral features. Density functional theory calculations are performed at the BP86 level to search for the global minima of both the anionic and neutral clusters. The calculated vertical electron detachment energies for the global minimum and low-lying isomers are compared with the experimental data. Strong boron-boron bonding is found to dominate the lowest energy structures of Ta2Bx- and Ta2Bx (x = 2-5), which are shown to be bipyramidal with the boron atoms forming an equatorial belt around the Ta-Ta dimer. Strong Ta-Ta bonding is observed in Ta2Bx- and Ta2Bx for x = 2-4, whereas the Ta-Ta distance is increased significantly in Ta2B5-and Ta2B5. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4776769]