Electronic structure and chemical stabilization of C28 fullerene Original Research Article

The ab initio density functional theory (DFT) method was used to carry out self-consistent calculations of the electronic structure of “mixed” C28-based fullerenes: (1) heterofullerenes C24N4, C24B4, (2) exohedral complexes C28M4 (M=H, F, Cl, Br), (3) endohedral complexes M@C28 with 2p- (M=B, C, N, O), and (4) endohedral complexes M@C28 with 3d-atoms (M=Sc, Ti, V, Cr, Fe, Cu). The electronic structure, charge distributions, chemical bonding and comparative stability in the series of these complexes are analyzed. Studying different types of C28 functionalization, we established that the optimum chemical stability conditions are met for (1) C24B4 from the series of heterofullerenes, (2) C28F4 from the series of exocomplexes, (3) B@C28 from the series of endocomplexes with participation of 2p-atoms, and (4) Ti@C28 from the series of endocomplexes with participation of 3d-atoms. Possible mechanisms of C28 stabilization are discussed depending on the method of functionalization and the type of a “guest” atom.