A NEW CHARACTERIZATION OF LANTHANUM-ENDOHEDRAL AND SCANDIUM-ENDOHEDRAL METALLOFULLERENES

Several endohedral metallofullerenes involving La and Sc atom(s) were characterized by electron spin resonance (ESR) and mass spectrometry. In particular, new types of lanthanofullerenes including LaC76 and LaC84 were produced and extracted by a newly developed fullerene arc-generator equipped with an anaerobic (air-free) sampling and extraction mechanism of metallofullerenes. The newly extracted lanthanofullerenes exhibit equally spaced octet ESR lines of equal signal intensities with different hyperfine coupling constants (0.44 G, 3.15 G, 2.12 G) and g values (2.0043, 2.0042, 2.0010). These lanthanofullerenes are found to be air sensitive, in contrast to reported metallofullerenes such as La-C82, Y-C82, and Sc-C82. The probable candidates for these fullerenes are presented, including LaC76 and LaC84. Furthermore, Sc-C82 and La-C82 fullerenes can be well separated from Sc3-C82 and La-C84 respectively, by liquid chromatography with an ethanol-deactivated silica-gel column.