Beltlike $C_{60}^{-}$ Electron Spin Density Distribution in the Organic Ferromagnet TDAE- $C_{60}$

The observed huge increase in the width of the ${}^{13}\mathrm{C}$ NMR spectra of TDAE- ${\mathrm{C}}_{60}$ in the middle of the ferromagnetic phase at 10 K is due to a Jahn-Teller distortion of the ${\mathrm{C}}_{60}^{-}$ ions which becomes visible in view of the resulting changes in the Fermi contact electron- ${}^{13}\mathrm{C}$ NMR shifts. The shape of the ${}^{13}\mathrm{C}$ spectra allows for a direct determination of the beltlike redistribution of the unpaired electron spin density on the ${\mathrm{C}}_{60}^{-}$ ions, which is responsible for the relatively high ferromagnetic transition temperature in this purely organic system.