Structure and electronic properties of hollow-caged C₆₀ fullerene-derived (MN₄)_nC_6(10-n) (M = Zn, Mg, Fe, n = 1-6) complexes

Unique hollow-caged (MN₄)_nC_6(10-n) (M = Zn, Mg, Fe, n = 1-6) complexes designed by introduction of n porphyrinoid fragments in C₆₀ fullerene structure were proposed and the atomic and electronic structures were calculated using LC-DFT MPWB95 and M06 potentials and 6-311G(d)/6-31G(d) basis sets. The complexes were optimized using various symmetric configurations from the highest O_h to the lowest C₁ point groups in different spin states from S = 0 (singlet) to S = 7 (quindectet) for M 5 Fe to define energetically preferable atomic and electronic structures. Several metastable complexes were determined and the key role of the metal ions in stabilization of the atomic structure of the complexes was revealed. For Fe₆N₂₄C₂₄, the minimum energy was reported for C_2h, D_2h, and D_4h symmetry of pentet state S = 2, so the complex can be regarded as unique molecular magnet. It was found that the metal partial density of states determine the nature of HOMO and LUMO levels making the clusters promising catalysts.