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 C(58)(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 C(60)(6)(-). The predicted NICS values may be useful for the identification of the heterofullerenes through their endohedral (3)He NMR chemical shifts. Compared to C(60), the dimerization of C(58)(BN) is calculated to be more exothermic by 16 kcal/mol.