We studied the structural, electronic and magnetic properties of small Fen clusters (n¼2–7) endohedrally doped in icosahedral C60 and C80 fullerenes using first principles calculations based on the density functional theory. It is found that the encapsulated Fen clusters inside icosahedral C80 are energetically favorable while Fen@C60 metallofullerene nano-cages are not. The binding energies of the Fen encapsulated in C60 are positive and increase with the number of iron atoms (n) while those of the Fen@C80 are negative and their absolute values increase up to n¼6. The encapsulation does not significantly change the enclosed cluster structure, but the total magnetic moment of the larger clusters reduces due to a stronger Fe–C hybridization.

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