ANAEROBIC SAMPLING AND CHARACTERIZATION OF LANTHANOFULLERENES - EXTRACTION OF LAC76 AND OTHER LAC(2N)

Several new types of lanthofullerenes including LaC76 have been produced and extracted by a newly developed fullerene arc generator equipped with an anaerobic (air-free) sampling and extraction mechanism of metallofullerenes. Other than the reporterd LaC82, at least three different lanthanum metallofullerenes have been extracted by toluene and observed by ESR and mass spectrometry under anaerobic sampling conditions. The newly extracted lanthanofullerenes exhibit equally-spaced octet ESR lines of equal signal intensities with different hyperfine coupling constants (0.44, 3.15, 2.12 G) and g values (2.0043, 2.0042, 2.0010). Furthermore, these lanthanofullerenes are found to be air-sensitive and in particular, the ESR signal intensity for one of the newly found metallofullerenes has decreased drastically to less than 5% of the original intensity when the sample was exposed to air for 5 days. The probable candidates for these fullerenes are presented, including LaC76 and LaC84.