Bridging the Gap between Electrochemical and Organometallic Activation: Benzyl Chloride Reduction at Silver Cathodes

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TitleBridging the Gap between Electrochemical and Organometallic Activation: Benzyl Chloride Reduction at Silver Cathodes
Publication TypeJournal Article
Year of Publication2010
AuthorsHuang, YF, Wu DY, Wang A, Ren B, Rondinini S, Tian ZQ, Amatore C
JournalJournal of the American Chemical Society
Volume132
Issue48
Pagination17199-17210
Date PublishedDec
ISBN Number0002-7863
Accession NumberISI:000285080400028
Abstract

Integration of voltammetry, surface-enhanced Raman spectroscopy (SEAS), and density functional theory (DFT) has allowed unraveling the mechanistic origin of the exceptional electrocatalytic properties of silver cathodes during the reduction of benzyl chloride. At inert electrodes the initial reduction proceeds through a concerted direct electron transfer yielding a benzyl radical as the first intermediate. Conversely, at silver electrodes it involves an uphill preadsorption of benzyl chloride onto the silver cathode. Reduction of this adduct affords a species tentatively described as a distorted benzyl radical anion stabilized by the silver surface. This transient species rapidly evolves to yield ultimately a benzyl radical bound onto the silver surface, the latter being reduced into a benzyl-silver anionic adduct which eventually dissociates into a free benzyl anion at more negative potentials. Within this framework, the exceptional electrocatalytic properties of silver cathodes stem from the fact that they drastically modify the mechanism of the 2e-reduction pathway through a direct consequence of the electrophilicity of silver cathode surfaces toward organic halides. This mechanism contrasts drastically with any of those tentatively invoked previously, and bridges classical electroreduction mechanisms and oxidative additions similar to those occurring during organometallic homogeneous activation of organic halides by low-valent transition-metal complexes.

URL<Go to ISI>://000285080400028
DOI10.1021/ja106049c
Short TitleBridging the Gap between Electrochemical and Organometallic Activation: Benzyl Chloride Reduction at Silver Cathodes
Unit: 
UMR 8640