C-13 HYPERFINE COUPLING-CONSTANTS IN MUC(60)

C-13 hyperfine coupling constants of the MuC(60) radical have been mea sured by muon level-crossing spectroscopy, using a dilute solution of 99% enriched C-13(60) in decalin. The signs as well as the magnitudes of the hyperfine constants were determined. The results range from 52. 6 to -25.4 MHz and support those calculations which predict an extende d distribution of unpaired electron spin density in radical adducts of fullerenes. The hyperfine constants are consistent with published ele ctron spin resonance results for (CD3)(3)CC60, but contradict a recent report for HC60, where a considerably smaller value is reported for t he largest splitting.