Exploring electronic structures for the most stable isomers of C12B6N6 and B6N6C12 heterofullerenes based on NMR, NICS and NBO analysis: A DFT study

DFT calculations are applied to evaluate the effects of atomic arrangements of dopant atoms on electronic features of the most stable structures of (BC2N)6 including both C24 fullerene doped with six BN units (C12B6N6; model 1–7) and B12N12 nanocage doped with six CC units (B6N6C12; model 8–15). Our study reveals a relation between local structures, Cα, Cβ, Cγ, and Cδ within the molecules and 13C NMR signals. This is also observed with natural charges, so that the increase of negative charge on carbon is along with more shielding of corresponding carbon. All BN-substituted species (model 1–7) with the negative calculated NICS at their cage center are predicted to be aromatic, in contrast to C24 (NICS=±37). The predicted NICS values may be useful for the identification of the heterofullerenes through their endohedral 3He NMR chemical shifts.