Structural and electrochemical studies of Sm@D-3h-C-74 reveal a weak metal-cage interaction and a small band gap species

A metallofullerene Sm@D-3h-C-74 that contains a divalent rare-earth metal has been studied structurally and electrochemically. The crystallographic analysis revealed that the endohedral Sm atom is more or less motional rather than being localized at a site where the pyracylene motif is nearby. This suggests a weaker metal-pyracylene interaction in Sm@D-3h-C-74 relative to that in MII@C-74 (M Group II metal), thus confirming the importance of the metal variety. The electrochemical studies showed a major difference between the redox properties of Sm@D-3h-C-74 and other Sm-fullerenes and indicated a small band gap for the title compound.