Hydrogen and proton exchange at carbon. Imbalanced transition state and mechanism crossover |
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Authors: | Cyrille Costentin,Jean-Michel Savé ant |
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Affiliation: | Département de Chimie Moléculaire, Université Grenoble-Alpes, CNRS, UMR 5250, 38000 Grenoble France.; Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex 13 France ; Université Paris Diderot, Sorbonne Paris Cité, Laboratoire d''Electrochimie Moléculaire, Unité Mixte de Recherche Université – CNRS No. 7591, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205 Paris Cedex 13 France, |
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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.Using the remarkable study of C–H oxidation of substituted fluorenyl-benzoates as an example, we have shown that a mechanism crossover takes place upon decreasing the driving force, from a CPET pathway to a PTET pathway. |
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