ISOLATION OF AN ESR-ACTIVE METALLOFULLERENE OF LA-AT-C-82

The ESR-active lanthanofullerene La@C-82 has been isolated from various hollow fullerenes by an efficient single-stage chromatographic separation process. Pyrenylethyl-silica was used as a stationary phase with toluene as an eluent. Lanthanum-containing fullerenes were prepared by the are heating of metal-impregnated graphite rods in a He atmosphere. Fast atom bombardment mass analysis of the isolated sample confirmed the isolation of La@C-82. ESR absorption spectra of the present sample prove the separation of a La@C-82 isomer with a 1.15-G hyperfine splitting. The UV-vis-near-IR absorption spectra of the sample reveal near-IR absorption peaks which are characteristic of the fullerene radical