Photoalkylation of C-60 by alkylcobalt(III) complexes

Photolysis of a benzonitrile solution of alkylcobalt(III) complexes, [RCo(D H)(2)py] (R = Me and PhCH2, (DH)(2) = bis(dimethylglyoximato), py = pyridin e) in the presence of C-60 by using visible light results in alkylation of C-60 to yield R2C60. The excited state of [RCo(DH)(2)py] rather than C-60 i s responsible for the photoalkylation of C-60, since the action spectrum fo r formation of R2C60 agrees with the absorption spectrum of [RCo(DH)(2)py] which is quite different from that of C-60 The photoalkylation of C-60 is r etarded by a radical trapping reagent such as 2,2,6,6-tetramethyl-1-piperid inyloxyl radical (TEMPO). This indicates that photoalkylation of C-60 proce eds via photocleavage of the cobalt-carbon bond of [RCo(DH)(2)py]. The inte rmediate benzyl radical produced by the photocleavage reaction of [PhCH2Co( DH)(2)py] is detected by ESR.