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

Abstract

Equilibrium structures of auropolyboroenes [Au₂(B₄)_xB₃]⁻, [Au₂(B₄)_xB₂]²⁻ and [Au₂(B₄)_xB]⁺ (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 σ and π 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.