CORRELATIONS BETWEEN BOND ORDER AND BOND-LENGTH IN THE ELECTRON-DEFICIENT CLOSO-BORANES

In the closo-boranes, the B-B bond distances vary widely, from 1.580 t o 1.990 angstrom. These large variations are consistent with the notio n of highly delocalized skeletal bonding in electron-deficient polyhed ral clusters. In this paper, we show correlations between B-B bond dis tances and four different calculated bond order indices: (1) Wade's fr actional bond orders; (2) Coulson's bond orders from three-dimensional Huckel MO theory; (3) Mulliken bond populations from extended Huckel MO theory, and (4) Mulliken bond populations from ab initio SCF MO cal culations.