Abstract
Localized molecular orbitals (LMO’s) have been calculated for the 1,2 and 1,6 isomers of C2B4H6 by the Edmiston-Ruedenberg procedure. The 1,2 isomer is the first example found in LMO calculations of the existence of the open three-center bond, and it occurs here only for the BCB nuclear configuration. The LMO structure for the 1,6 isomer is best interpreted in terms of fractional three-center bonding. We discuss the implications of these results for the general application of topological methods to boranes and carboranes.