Sc2 dimer in IPR-violated C66 fullerene: a covalent bonded metallofullerene

The structure of an IPR-violated metallofullerene Sc2@C66 has been determined in the electron density level by the MEM/Rietveld method using synchrotron radiation powder data. The fundamental structure has been obtained by the Rietveld analysis. The cage structure of C66 has been unambiguously identified as that of Isomer No. 4348. The obtained charge density by the MEM analysis shows that the encapsulated two Sc atoms form the covalent bonded Sc2 dimer and that the charge density of dimer is overlapping with that of C66 cage, indicating the existence of a covalent bond character between Sc2 and the carbon cage.