NEW ELECTRON-SPIN-RESONANCE AND MASS-SPECTROMETRIC STUDIES OF METALLOFULLERENES

The preparation by are vaporization of graphite rods of metal-containing fullerene samples with metals inside the fullerene molecules is described. The metals lanthanum, scandium, holmium and yttrium were used for this study. Results in mass spectrometry confirm the existence and stability of several Me@C-82 species. ESR spectroscopic measurements of metallofullerene samples in the solid state and in tetrachloroethane solution favour the existence of endohedral systems. The splitting of the ESR spectra is interpreted by isotropic hyperfine coupling of an unpaired electron with the nuclear magnetic moment of a metal ion inside a fullerene molecule. It is concluded that the metal atoms exist in ionic form in endohedral fullerenes both in solid and liquid state of the fullerene. Furthermore it is shown that there is more than one stable position of the metal ion inside the fullerene molecule.