Evidence for the transition from S_N to ET mechanism in the reaction of arene radical anion with alkyl halide evoked by the introduction of an electron withdrawing substituent into radical anion

The interaction of potassium salts of benzonitrile and 1.4-dicyanobenzene radical anions with cyclopropylmethyl bromide provides benzylcyclopropane, in the first case, and 4-alkyl- benzonitriles together with 2-alkyl-1,4-dicyanobenzenes containing both cyclopropylmethyl and it's isomeric 3-butenyl fragment, in the second case. These results provide evidence for the change of reaction mechanism from S_N to ET.