[en] Hypercoordinate boron is most unusual, leading to considerable theoretical and experimental research on the parent BH₅ molecule. The deprotonation energies of BH₅ and the related molecules AlH₅ and GaH₅ have been of particular interest. Here the energy differences for XH₅->XH₄^-+H(X=BandAl) are computed to be 332.4 and 326.3kcalmol^-1, respectively, with an aug-cc-pVQZ basis set at the CCSD(T) level of theory. Vibrational frequencies for BH₄^- and AlH₄^- are also reported as 1098, 1210, 2263, and 2284cm^-1 and 760, 779, 1658, and 1745cm^-1, respectively, again at the CCSD(T) aug-cc-pVQZ level of theory. Comparisons with the valence isoelectronic GaH₅ molecule are made