BN ALTERNANTS - BORON-NITRIDE CAGES AND POLYMERS

BN alternants with barons and nitrogens fully replacing alternant sets of carbons in an alternant hydrocarbon form a special class of specie s of natural interest. The Huckel model for general BN alternants and certain extended Huckel models for ''regular'' BN alternants are shown to be simply soluble in terms of the eigensolutions for the correspon ding alternant hydrocarbons. The difference in the electronegativities for boron and nitrogen implies the opening of HOMO-LUMO gaps for alte rnant BN clusters-or equivalently the opening of band gaps (at the Fer mi energy) for BN alternant polymers. Infinite classes first of octahe dral-symmetry fullerenoid cages and second of ''buckytube'' polymers a re considered.