EPR-SPECTRA OF PARTIALLY FLUORINATED ALKYL-C-60 RADICALS AND A THEORETICAL-STUDY OF INTERACTIONS ON THE C-60 SURFACE

The EPR spectra of seven partially fluorinated derivatives of methyl-, ethyl-, and isopropyl-C-60 radicals have been studied. The equilibriu m configuration of-each was deduced from their proton and F-19 hyperfi ne interactions. if one or more of the hydrogens of CH3Cl60 are replac ed by CF3, F, or CH3, there is a competition among them for the positi on over the pentagon adjacent to the C-C-60 bond. The order CF3 > F > H > CH3 follows closely their respective inductive effect parameters a r. Quantum chemical calculations at the INDO/UHF level have been used to rationalize this hierarchy in terms of charge separation on the C-6 0 surface.