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Laboratoire d'Electrochimie Moleculaire, LEM, Paris

UMR CNRS - Université Paris Diderot - Paris France

   
 
Master Frontiers in Chemistry | UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie Université de Paris Master Chimie Sorbonne Paris Cité UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie
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Université Paris Diderot
Université de Paris CNRS, Centre National de la Recherche Scientifique
 
 


Le LEM - Publications: Abstracts

Publication 640

Chem. Phys. Chem. 10, 191-198, 2009.
DOI: 10.1002/cphc.200800361  j
 

Concerted and stepwise proton coupled electron transfers in water. Mechanisms of aquo/ hydroxo complex redox couples illustrated by the oxidative electrochemistry of OsII(bpy)2pyOH2]2+.

Cyrille Costentin, Marc Robert, Jean-Michel Savéant, and Anne-Lucie Teillout

Laboratoire d‘Electrochimie Moléculaire, UMR CNRS 7591 Université Paris Diderot, 2 place Jussieu 75251 Paris Cedex 05 (France)

 


Successive oxidation of transition metal(II) aqua complexes (MIIOH2 to MIIIOH) is a domain in which proton-coupled electron transfer reactions are extremely common. The mechanism of these PCET reactions - concerted or stepwise - is an important issue in the understanding and design of natural or artificial systems catalyzing the formation of dioxygen by four-electron oxidation of water. Concerted proton-coupled electron transfer from an aqua metal(II) to a hydroxo metal(III) complex requires the close proximity of a proton-accepting group with a pK value between those of the aqua complexes. Otherwise, stepwise electron-proton or proton-electron pathways involving high-energy intermediates are followed. Concerted proton-electron pathways involving water as proton-acceptor or proton-donor group are inefficient. Cyclic voltammetry of the title complex in buffered aqueous solution and re-examination of previous results for the same complex attached to an electrode surface are used to establish these conclusions, which provide a starting point on the route to higher degrees of oxidation, such as those involved in the catalysis of water oxidation.

 
   
 
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