ELECTROCHEMICAL-BEHAVIOR AND EPR OF RADICAL-ANIONS OF PERFLUOROALKYL-SUBSTITUTED OLEFINS

Some perfluoroalkylolefins are shown to undergo electrochemical one-el ectron reduction to the corresponding radical anions at potential valu es which strongly depend on the structure of the substituents. In thes e cases the voltammetric reduction peak is chemically reversible, and a further one-electron transfer, affording the corresponding dianions, is detected at more negative potentials. For these substrates, at app ropriate temperatures, the free radical anions are stable enough to be accumulated by macroscale electrolysis and investigated by EPR. The s pectra are characterized by fairly large hyperfine couplings of F-19 i n alpha, beta, and gamma positions relative to the pi carbon centers a nd by line width effects due to restricted rotations of the perfluoroa lkyl groups around the C-C single bonds. The case of tetrakis(trifluor omethyl)ethylene has been analyzed in detail, and it is concluded that the rotation motion of the four trifluoromethyl groups should be in p art correlated.