Structures and bonding of auropolyboroenes [Au2(B4)xB3]-, [Au2(B4)xB2]2- and [Au2(B4)xB]+ (x=2, 3): comparison with dihydride polyboroenes

Equilibrium structures of auropolyboroenes [Au-2(B-4)(x)B-3](-), [Au-2(B-4)(x)B-2](2-) and [Au-2(B-4)(x)B](+) (x = 2, 3) are obtained from density functional theory-based calculations. Results show that the ground states of Au2B9+, Au2B13+ and Au2B142- can be obtained by adding two Au atoms to the corresponding ground-state pure boron clusters. For Au2B102-, Au2B11-, Au2B142- and Au2B15-, the ladder structures are proven to be the ground states at TPSS, OVGF, and CCSD(T) levels, which is similar to that of dihydride polyboroenes. AdNDP analysis indicates that the two rows of boron atoms in these auropolyboroenes are bonded by delocalized three-, four-, or five-center sigma and pi bonds. Especially, the dominant bonding patterns in Au2B11- and Au2B142- bear similarities to those of dihydride polyboroenes. The photoelectron spectroscopy (PES) spectra for anionic clusters were simulated to facilitate the experimental PES spectra. In addition, the fragmentation energies and products against different decay channels are estimated and discussed.