Electrochemistry is by birth and by essence an interfacial, and therefore an essentially heterogeneous technique. Thus, at least at first glance, electrochemistry and homogeneous catalysis appear as two independent chemical fields with almost no affinity or overlay especially when the homogeneous reaction do not involve effective electron transfers.
However, this most common appreciation leaves apart another great property of electrochemical methods which is based on their analytical properties particularly when they are based on ultramicroelectrodes. Thus, provided they are electroactive, very short-lived crucial intermediates may be detected, characterized and their kinetic evolution during homogeneous catalytic cycles followed quantitatively. We wish to show in this lecture that electrochemical approaches, alone or in combination with usual spectroscopies or DFT studies, can be used with great profit to achieve a better mechanistic understanding of key processes in homogeneous catalysis of organic reactions by transition metal complexes, even when these catalytic cycles do not involve any effective electron transfer step.
It will also be shown how the use of the concepts borne from such mechanistic studies may lead to the validation of empirical findings or the proposal of actions for the design of more efficient catalytic cycles. In particular these will serve to discuss some features that potentially good catalytic cycles must possess, thus explaining why intuitive approaches which are based in fact on stoichiometric studies do not always lead to efficient catalytic strategies.
These aspects will be discussed and illustrated on the basis of a few selected examples taken from the research of our group in the field of homogeneous catalysis of cross-coupling reactions by palladium complexes and related to the Nobel Prize in Chemistry delivered in 2010.