Crystallographic Characterization of Lu2O@Cs(6)‐C82 and Er2O@Cs(6)‐C82: The Role of Metal Species on Cluster Configuration†

Abstract

Comprehensive SummaryIntramolecular interactions are fundamental for the unique structures and outstanding properties of metallofullerenes. However, how the internal metal species interplay with the cluster configuration inside oxide clusterfullerenes remains poorly understood. Herein, we successfully captured two oxide clusterfullerenes with different metals, namely, Lu2O@C82 and Er2O@C82, to elucidate the role of metal species in tuning cluster configuration. The two molecules have been fully characterized by mass spectrometry, Vis‐NIR absorption spectroscopy, cyclic voltammetry, and single‐crystal X‐ray diffraction. Crystallographic data show that their isomeric cages were both determined as Cs(6)‐C82. Further structural analysis reveals that the Lu1‐O‐Lu2 angle value in Lu2O@Cs(6)‐C82 is much larger than the Er1‐O‐Er2 angle value in Er2O@Cs(6)‐C82, indicating that the configuration of the endohedral oxide clusters is flexible and dependent on the metal ion radius. Additionally, electrochemical studies suggest that the variation in entrapped metal species causes differences in redox properties, for which the first oxidation and first reduction potentials of Lu2O@Cs(6)‐C82 are shifted positively and negatively, respectively, compared to the counterparts of Er2O@Cs(6)‐C82, resulting in a larger electrochemical band‐gap.