Anomalous endohedral structure of Gd@C₈₂ metallofullerenes

An anomalous endohedral structure of Gd@C₈₂ metallofullerenes has been revealed by synchrotron radiation powder structure analysis by using the maximum entropy method. The Gd@C₈₂ metallofullerene has C₈₂-C_2V cage structure as for Sc@C₈₂ and La@C₈₂ fullerenes. The Gd atom is located in the vicinity of the C-C double bond on the C₂ molecular axis in the C₈₂/C_2V cage, which is the opposite end of the six-membered ring where Sc and La atoms in Sc@C₈₂ and La@C₈₂ are known to be placed. Furthermore, a significant overlap of the electron density distribution has been found between Gd atoms and carbon cages. A significantly polarized distribution of electrons has also been found on the carbon cage around the encapsulated Gd atom.