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-[MoX(2)(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)--> Mo(0) reduction 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.