Dialane anions can be formed via a single three-center two-electron (3c-2e) or two-center one-electron (2c-1e) bond. The 2c-1e bonded anion Al2H6-(D-3d) and the 3c-2e bonded anion Al2H6-(C-s) have significant thermodynamic stabilities with respect to the neutral Al2H6(D-2h) and correspond to 0.22 and 0.32 eV of the adiabatic electron affinities, respectively. In particular, the 2c-1e bond plays an essential role in stabilizing the Al2H6-(D-3d) anion.