Isolation of CeLu2N@Ih-C80 through a Non-Chromatographic, Two-Step Chemical Process and Crystallographic Characterization of the Pyramidalized CeLu2N within the Icosahedral Cage

By combining two chemical methods of purification, 4 mg of purified CeLu2N@C80 was readily isolated from 500 mg of carbon soot extract without the use of recycling HPLC, a method which has previously been necessary to obtain pure samples of endohedral fullerenes. In stage 1, CeLu2N@C80 was selectively precipitated by virtue of its low first oxidation potential (+0.01 V) and the judicious choice of MgCl2 as the Lewis acid precipitant. For stage 2, we used a stir and filter approach (SAFA), which employed the electron‐rich NH2 groups immobilized on silica gel to selectively bind residual endohedrals and higher cage fullerenes that were contaminants from stage 1. Crystallographic analysis of CeLu2N@C80 in the co‐crystal CeLu2N@Ih‐C80⋅Ni(octaethylporphyrin)⋅2(toluene) reveals that the Ih‐C80 cage is present with a pyramidalized CeLu2N unit inside. Combined strength: Purified CeLu2N@C80 was isolated without using HPLC by selective precipitation with MgCl2 followed by removal of residual empty cage and endohedral fullerenes by treatment with silica gel functionalized with amino groups (see figure). Crystallographic analysis of CeLu2N@C80 reveals that the Ih‐C80 cage is present with a pyramidalized CeLu2N unit inside.