Assessment of the Stability of Heterohedral Fullerenes: A Theoretical Analysis of C60-xNx and C60-xBx Where x = 1 and 2

Abstract

In this work we discuss limitations in the stability of monosubstituted heterohedral fullerenes. Both quantum and molecular mechanical approaches are used to understand the limits in bonding and structural characteristics of these materials. Both the electronic structure calculations and the molecular mechanics study suggest that greater inherent stability exists in the monosubstituted boron fullerene compared with the equivalent nitrogen analog. This is somewhat consistent with the sparse experimental information provided for N-doped fullerenes. In addition, structural comparisons show significantly greater distortion of the fullerene framework for the nitrogen-substituted material. Electronic structure calculations predict greater disruption of bonding near the substitution site for C{sub 59}N in comparison with C{sub 59}B, and the energy trends from these calculations suggest that the stability of the C{sub 59}N is considerably lower than that of C{sub 59}B. Furthermore, the electronic structure calculations suggest that C{sub 59}N{sup +} may be more stable than the parent neutral material. Disubstituted heterohedral fullerenes have been analyzed utilizing similar electronic requisites for stability. 25 refs., 5 figs., 5 tabs.