ESR STUDIES OF THE REACTION OF ALKYL RADICALS WITH C-60

Photolytically and thermally generated alkyl radicals (R. = tert-butyl, 1-adamantyl, isopropyl, ethyl, and benzyl) react with C60 to form R-C60. radical adducts which have been identified by the proton and C-13 hyperfine interactions obtained from their electron spin resonance spectra. Consideration of the C-13 spectra shows that the unpaired electron in R-C60. is mostly confined to two fused, six-membered rings on the C60 surface, having the substituent R at one of the points of fusion. Each half of the resulting radical structure of C(s) symmetry can be compared with a cyclohexadienyl radical. Extensive delocalization of the unpaired electron over the C60 sphere is ruled out.