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 C-24 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, C-alpha, C-beta, C-gamma, and C-delta within the molecules and C-13 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 C-24 (NICS = +/- 37). The predicted NICS values may be useful for the identification of the heterofullerenes through their endohedral He-3 NMR chemical shifts. (C) 2012 Elsevier B.V. All rights reserved.