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Published on: July 19, 2019
Hydrogen and proton exchange at carbon. Imbalanced transition state and mechanism crossover
Cyrille Costentin1,2, Jean-Michel Savéant3
1Département de Chimie Moléculaire, Université Grenoble-Alpes, CNRS, UMR 5250 38000 Grenoble France cyrille.costentin@univ-grenoble-alpes.fr.
Abstract:
A recent remarkable study of the C-H oxidation of substituted fluorenyl-benzoates together with the transfer of a proton to an internal receiving group by means of electron transfer outer-sphere oxidants, in the noteworthy absence of hydrogen-bonding interactions, is taken as an example to uncover the existence of a mechanism crossover, making the reaction pass from a CPET pathway to a PTET pathway as the driving force of the global reaction decreases. This was also the occasion to stress that considerations based on "imbalanced" or "asynchronous" transition states cannot replace activation/driving force models based on the quantum mechanical treatment of both electrons and transferring protons.
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