Mapping the Metal Positions inside Spherical C 80 Cages: Crystallographic and Theoretical Studies of Ce 2 @ D 5 h ‐C 80 and Ce 2 @ I h ‐C 80

The dynamic positions of the dimetallic cluster inside the mid‐sized spherical cages of C 80 –C 82 have been seldom studied, despite the high abundance of M 2 @C 2 n (2 n =80, 82) species among various endohedral metallofullerenes. Herein, using crystallographic methods, we first unambiguously map the metal positions for both Ce 2 @ D 5 h ‐C 80 and Ce 2 @ I h ‐C 80 , showing how the symmetry or geometrical change in cage structure can influence the motional behavior of the cluster. Inside the D 5 h cage, the primary cerium sites have been identified along a cage belt of the contiguous hexagons, which suggests the significant influence of such a cage motif on endohedral cluster motion. Further analysis revealed a distorted D 5 h cage owing to the “punch‐out” effect of cerium atoms. The consequence is the presence of two localized electrostatic potential minima inside the cage of ( D 5 h ‐C 80 ) 6− , thus reflecting the primary ionic cerium–cage interaction. In contrast, a different motional behavior of Ce 2 cluster was observed inside the I h cage. With the major cerium sites, the molecule of Ce 2 @ I h ‐C 80 presented an approximate D 2 h configuration. With the combined theoretical study, we propose that the additional unidentified influence of Ni II (OEP) (OEP=octaethylporphyrin) might be also relevant for the location of cerium sites inside the I h cage.