Cleavage of an aromatic carbon-heteroatom bond in a single step or successive steps?--A mechanistic distinction in the reduction of 5-bromo-1,3-dichloro-2-iodobenzene

The electrochemical reductive cleavage of the carbon-iodine bond in 5-bromo-1,3-dichloro-2-iodobenzene has been analyzed from the mechanistic point of view employing the Marcus theory of heterogeneous outer sphere electron transfer. The variation of the electrochemical transfer coefficient with potential has been estimated from the cyclic and convolution voltammetric studies. The comparison of the experimental reorganization energy with the theoretical predictions has revealed the existence of the radical anion of 5-bromo-1,3-dichloro-2-iodobenzene as a transient species.