Isolation and Crystallographic Characterization of Two, Nonisolated Pentagon Endohedral Fullerenes: Ho₃N@<i>C</i>₂(22010)‐C₇₈ and Tb₃N@<i>C</i>₂(22010)‐C₇₈

Abstract

Abstract Purified samples of Ho 3 N@ C 2 (22010)‐C 78 and Tb 3 N@ C 2 (22010)‐C 78 have been isolated by two distinct processes from the rich array of fullerenes and endohedral fullerenes present in carbon soot from graphite rods doped with Ho 2 O 3 or Tb 4 O 7 . Crystallographic analysis of the endohedral fullerenes as cocrystals with Ni(OEP) (in which OEP is the dianion of octaethylporphyrin) shows that both molecules contain the chiral C 2 (22010)‐C 78 cage. This cage does not obey the isolated pentagon rule (IPR) but has two sites where two pentagons share a common C−C bond. These pentalene units bind two of the metal ions, whereas the third metal resides near a hexagon of the cage. Inside the cages, the Ho 3 N or Tb 3 N unit is planar. Ho 3 N@ C 2 (22010)‐C 78 and Tb 3 N@ C 2 (22010)‐C 78 use the same cage previously found for Gd 3 N@ C 2 (22010)‐C 78 rather than the IPR‐obeying cage found in Sc 3 N@ D 3 h ‐C 78 .