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@D3h-C74 relative to that in M(II)@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.