ISOMERS AND C-13 HYPERFINE STRUCTURES OF METAL-ENCAPSULATED FULLERENES M-AT-THE-COST-OF-C82 (M = SC, Y, AND LA)

The formation of two isomers of C82 with a metal inside, M @ C82 (M = SC, Y, and La) was first identified by ESR spectroscopy. The production ratio of two isomers found for M @ C82 suggests that the cage structure of the isomers of M @ C82 is closely associated with those of the empty C82. However, contrary to the existence of four or more distinct isomers of empty C82, the observation of only two metallofullerene isomers strongly suggests that a metal is selectively encapsulated in the C82 cages with particular structures. An endohedral form of metal-containing C82 fullerene was established by observation of well-resolved ESR spectra of hyperfine coupling to C-13 in natural abundance on the carbon cages.