The geometrical and electronic structures of the electron-deficient dialuminum aurides Al2Aun0/- and hybrid boron-aluminum aurides BAlAun0/- (n=1-3) are systematically investigated based on the density and wave function theories. Ab initio theoretical evidence strongly suggests that bridging gold atoms exist in the ground states of C2v Al2Au- (3B1), C2v Al2Au (2B1), C2v Al2Au2- (2A1), C2v Al2Au2 (1A1), Cs Al2Au3- (1A'), and D3h Al2Au3 (2A1), which prove to possess an Al-Au-Al τ bond. For BAlAun0/- (n=1-3) mixed clusters, bridging B-Au-Al units only exist in Cs BAlAu3- (1A') and Cs BAlAu3 (2A'), whereas Cs BAlAu- (3A″), Cs BAlAu (2A″), Cs BAlAu2- (2A'), and Cs BAlAu2 (1A') do not possess a bridging gold, as demonstrated by the fact that B-Al and B-Au exhibit significantly stronger electronic interaction than Al-Au in the same clusters. Orbital analyses indicate that Au 6s contributes approximately 98%~99% to the Au-based orbital in these Al-Au-Al/B-Au-Al interactions, whereas Au 5d contributes 1%~2%. The adiabatic and vertical detachment energies of Al2Aun- (n=1-3) are calculated to facilitate future experimental characterizations. The results obtained in this work establish an interesting τ bonding model (Al-Au-Al/B-Au-Al) for electron-deficient systems in which Au 6s plays a major factor.