Three-Dimensional Aromaticity in Polyhedral Boranes and Related Molecules

Chemical bonding models based on graph theory or tensor surface harmonic theory demonstrate the analogy between the aromaticity in two-dimensional planar polygonal hydrocarbons such as benzene and that in three-dimensional deltahedral borane anions of the type BnHn2- (6 < or = n < or = 12). Such models are supported both by diverse computational studies and experimental determinations of electron density distribution. Related methods can be used to study the chemical bonding in the boron polyhedra found in other structures including neutral binary boron hydrides, metallaboranes, various allotropes of elemental boron, and boron-rich solid-state metal borides.