Electrochemical Reduction of 4‐Nitrobenzyl Phenyl Thioether for Activation and Capture of CO 2

In this work, a new simple molecule, 4‐nitrobenzyl phenyl thioether ( 1 ), is prepared and used for controlling and tuning CO 2 reactivity in function of the electrode potential. The first part of the study is devoted to determining the electrochemical reduction mechanism of 1 in N,N ‐dimethylformamide under nitrogen. The compound shows a first reversible one‐electron transfer process, whereas the reaction cleavage of the C−S bond takes place after a second electron transfer process through a stepwise mechanism (thermodynamic and kinetic parameters are conveniently determined). In the second part of the study, the inert atmosphere was replaced by a CO 2 atmosphere. At low potential values, compound 1 acts as a redox mediator that allows the reduction of CO 2 at ca. −1.2 V vs. SCE. The electrochemical generation of 1 2− at more negative potential values leads to a C−S bond cleavage reaction that yields the corresponding nitrobenzyl and thiosulfate anions, which react with CO 2 . The nitro aromatic anion derivative makes it possible to obtain electrocarboxylated derivatives, whereas the thiophenolate anion captures CO 2 reversibly. Hence, this research opens a new way of tuning and controlling the reaction processes associated with CO 2 from homogenous catalysis at low negative potentials, to electrocarboxylation processes passing to CO 2 reversible electrochemically triggered adsorption processes.