The Occurrence of π Molecular Orbitals in Planar Boron Clusters

Abstract

Abstract The energy of the lowest π molecular orbital in a planar boron cluster can be estimated from the connectivity of constituent boron atoms, or the mean valency of the boron atoms. Low-energy π molecular orbitals were then predicted to occur in all realistic planar polycyclic boron clusters. In fact, all such boron clusters studied have one or more π molecular orbitals with two or more π electrons. They are aromatic with positive topological resonance energies. π Conjugation and aromaticity must be totally or partially responsible for the planarity of low-energy boron clusters.