BN-doped fullerenes: An NICS characterization

Heterofullerenes C-58(BN), C-54(BN)(3), C-48(BN)(6), and C-12(BN)(24) and their hexaanions as well as the C58(BN) dimer have been investigated by ab initio calculations. On the basis of the computed nucleus independent chemical shifts (NICS) at the cage center and also at the center of individual rings, BN-doped fullerenes C-58(BN), C-54(BN)(3), and C-48(BN)(6) are slightly more aromatic than C-60, whereas the corresponding hexaanions are significantly less aromatic than CG(60)(6-). The predicted NICS values may be useful for the identification of the heterofullerenes through their endohedral He-3 NMR chemical shifts. Compared to C-60, the dimerization of C-58(BN) is calculated to be more exothermic by 16 kcal/mol.