Electrocatalytic reduction of organohalides mediated by the dihalo-molybdenum phosphinic complexes trans-[MoX2(Ph2PCH2CH2PPh2)2] (X = I, Br)—A mechanistic study by cyclic voltammetry digital simulation

Abstract

trans-[MoX₂(dppe)₂] (X = I, Br) act as inner-sphere electron-transfer mediators for the electrocatalytic reduction of organohalides RX to R˙ + X⁻, at both Mo^II→ Mo^I and Mo^I→ Mo⁰reduction processes, each of them involving a cathodically induced heterolytic metal–halide bond cleavage with liberation of X⁻ that is followed by addition of RX to the metal. Digital simulation of cyclic voltammetry at a wide range of scan rates allowed to estimate the rate constants of the various chemical steps for both electrocatalytic cycles, which were compared in terms of Mo–X bond dissociation energies, electronic and stereochemical effects.