Electron-Transfer Processes in the Electrophilic Cleavage of Cobalt-Carbon Bonds of Alkylcobalt(III) Complexes with Iodine

Contribution of the electron-transfer processes in the cleavage of cobalt-carbon bonds of alkylcobalt(III) complexes cis-[R₂Co-(bpy)₂]⁺(R = Me, Et, PhCH₂; bpy = 2,2ʹ-bipyridine), trans-[Me₂Co(DpnH)] (DpnH = 11-hydroxy-2,3,9,10-tetramethyl-1,4,8,1 1-tetraazaundeca-1,3,8,10-tetraen-1-olate), and [RCo(DH)₂py] (R = Me, Et, PhCH₂; (DH)₂= bis(dimethylglyoximato); py = pyridine) with iodine has been studied by detecting the products that could arise only via electron-transfer processes as well as by the kinetic comparison between the electrophilic reactions of iodine with alkylcobalt(III) complexes and the electron-transfer reactions of iodine with ferrocene derivatives in acetonitrile. The coupling products of alkyl groups of dialkylcobalt(III) complexes, derived from the corresponding dialkylcobalt(IV) complexes, are obtained in the cleavage reactions of dialkylcobalt(III) complexes with iodine, with alkyl iodides being the main products. The observed second-order rate constants for the cleavage reactions of alkylcobalt(III) complexes with iodine in acetonitrile at 298 K are compared with those of electron transfer from ferrocene derivatives to iodine, based on the Marcus theory of electron transfer.