Octahydropentaborate anion ($[{\mathrm{B}}_5{\mathrm{H}}_8{]}^{-}$)

$[{\mathrm{B}}_5{\mathrm{H}}_8{]}^{-}$, the bridge-deprotonated conjugate base of pentaborane(9). Its five-vertex framework has seven skeletal pairs and is nido.