Boron−Nitrogen (BN) Substitution Patterns in C/BN Hybrid Fullerenes: C60-2x(BN)x (x = 1−7)

Abstract

Semiempirical AM1 and MNDO and density functional theory (B3LYP/3-21G and 6-31G*) are used to examine the relative stability of various isomers of successive BN substituted fullerenes C60-2x(BN)x, where x=1−7. It is found that stability is enhanced by keeping BN units and BN filled hexagons adjacent to one another. Successive BN substitution prefers N site attachment to the existing BN chain. The localization of MOs shows that lone-pairs of nitrogen atoms reside “inside” the cage, which may be the reason for outward displacement of N atoms. Geometric parameters and charge distribution of the carbon region of hybrid fullerenes are not much perturbed by BN substitution. Band gap (HOMO−LUMO gap), ionization potential, and electron affinities strongly depend on the number of BN units and filling of the hexagons. Partially BN filled hexagons or unsaturated BN fullerenes have a stronger effect than completely filled hexagons on perturbing these properties.