The ErnSc3-nN@C80 (n = 0−3) family of four endohedral fullerenes has been prepared by vaporization of graphite rods packed with 2% Sc2O3/3% Er2O3/95% graphite powder in a Kratschmer−Huffman fullerene generator under dynamic flow of helium and dinitrogen. ErSc2N@C80 has been isolated in pure form via three stages of high-pressure liquid chromatography and characterized by mass spectrometry. The first structure of a mixed metal endohedral, ErSc2N@C80, has been determined by single-crystal X-ray diffraction at 90 K on ErSc2N@C80·CoII(OEP)·1.5C6H6·0.3CHCl3, which was obtained by diffusion of a solution of ErSc2N@C80 in benzene into a solution of CoII(OEP) (OEP is the dianion of octaethylporphyrin) in chloroform. The structure of ErSc2N@C80 consists of a planar ErSc2N unit surrounded by an icosahedral C80 cage. The nominal Er−N distance is 2.089(9) A and the Sc−N distance is, as expected, shorter, 1.968(6) A. Despite its location within the C80 cage, the ErSc2N unit displays a remarkable degree of order within...