Density functional theory (DFT) at the hybrid B3LYP level has been applied to the polyhedral boranes BnHnz (n = 8 and 11, z = -2, -4, and -6) for comparison with isoelectronic germanium clusters Ge-n(z). The energy differences between the global minima and other higher energy borane structures are much larger relative to the case of the corresponding bare germanium clusters. Furthermore, for both B8H82- and B11H112-, the lowest energy computed structures are the corresponding experimentally observed most spherical deltahedra predicted by the Wade-Mingos rules, namely the D-2d bisdisphenoid and the C-2v edge-coalesced icosahedron, respectively. Only in the case of B8H82- is there a second structure close (+2.6 kcal/mol) to the D-2d bisdisphenoid global minimum, namely the C-2v bicapped trigonal prism corresponding to the "square" intermediate in a single diamond-square-diamond process that can lead to the experimentally observed room temperature fluxionality of B8H82-. Stable borane structures with 3-fold symmetry (e.g., D-3h, C-3v, etc.) are not found for boranes with 8- and 11-vertices, in contrast to the corresponding germanium clusters where stable structures derived from the D-3d bicapped octahedron and D3h pentacapped trigonal prism are found for the 8- and 11-vertex systems, respectively. The lowest energy structures found for the electron-rich boranes B8H84- and B11H114- are nido polyhedra derived from a closo deltahedron by removal of a relatively high degree vertex, as predicted by the Wade-Mingos rules. They relate to isoelectronic species found experimentally, e.g., B8H12 and R4C4B4H4 for B8H84- and C2B9H112- for B11H114-. Three structures were found for B11H116- with arachno type geometry having two open faces in accord with the Wade-Mingos rules.