Identifying a Needle in a Haystack: Isolation and Structural Characterization of Er2C94 as the Carbide Er2C2@D3(85)‐C92

A method has been developed for isolating a pure sample of Er2C94 from the myriad of fullerenes and endohedral fullerenes that are formed in the electric arc process. Crystallographic analysis of Er2C94 in a cocrystal formed with Ni(OEP) reveals that the molecule is the carbide Er2C2@D3(85)‐C92. Crystals of Er2C2@D3(85)‐C92⋅Ni(octaethylporphyrin)⋅2 C7H8 are isostructural with those of Sm2@D3(85)‐C92⋅Ni(octaethylporphyrin)⋅2 (chlorobenzene). Comparisons are made between the four crystallographically characterized endohedrals (Er2C2@D3(85)‐C92, Gd2C2@D3(85)‐C92, La2C2@D3(85)‐C92, and Sm2@D3(85)‐C92) that utilize the chiral D3(85)‐C92 cage. Fullerenes: A method has been developed for isolating a pure sample of Er2C94 from the myriad of fullerenes and endohedral fullerenes that are formed in the electric arc process. Crystallographic analysis of Er2C94 in a cocrystal formed with Ni(OEP) reveals that the molecule is the carbide Er2C2@D3(85)‐C92.