MAGNETIC-RESONANCE OF THE WEAK ORGANIC MAGNET TDAE-C-60

The charge transfer compound TDAE-C-60 (TDAE = tetrakis-dimethylamino- ethylene) is so far the only known C-60 based molecular ferromagnet. T he ESR spectra of TDAE-C-60 single crystals demonstrate that freshly g rown regularly shaped single crystals show at first an AFM (antiferrom agnetic)-like behavior which changes upon annealing at room temperatur e in vacuum to a FM (ferromagnetic) one. It thus seems that annealing induces a change in the relative orientation of the distorted C-60(-) ions resulting in a change in the sign of the effective magnetic inter actions between neighboring C-60(-) ions. A structural transition in t he TDAE methyl protons at 250 K seems to be connected with this proces s. Here we review the structure, the ESR spectra, the proton NMR spect ra and the C-13 NMR spectra of TDAE-C-60.