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Title: Theoretical Study of C–H Bond Cleavage via Concerted Proton-Coupled Electron Transfer in Fluorenyl-Benzoates

Abstract

Developing new strategies to activate and cleave C–H bonds is crucial for a broad range of applications. Currently a new method for C–H bond activation using multi-site concerted proton-coupled electron transfer (PCET) involving intermolecular electron transfer to an oxidant coupled to intramolecular proton transfer was reported. For a series of oxidants reacting with 2-(9H-fluoren-9-yl)benzoate, experimental studies revealed an atypical Brønsted α, defined as the slope of the logarithm of the PCET rate constant versus the logarithm of the equilibrium constant or the scaled driving force. Herein this reaction is modeled with a vibronically nonadiabatic PCET theory. Hydrogen tunneling, thermal sampling of the proton donor–acceptor mode, solute and solvent reorganization, and contributions from excited vibronic states are found to play important roles. The calculations qualitatively reproduce the experimental observation of a Brønsted α significantly less than 0.5 and explain this shallow slope in terms of exoergic processes between pairs of electron–proton vibronic states. These fundamental mechanistic insights may guide the design of more effective strategies for C–H bond activation and cleavage.

Authors:
 [1];  [1]; ORCiD logo [1]
  1. Yale Univ., New Haven, CT (United States)
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Energy Frontier Research Center (EFRC) Center for Molecular Electrocatalysis (CME)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Institutes of Health (NIH)
OSTI Identifier:
1566592
Grant/Contract Number:  
[AC05-76RL01830]
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
[ Journal Volume: 140; Journal Issue: 46]; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Sayfutyarova, Elvira R., Goldsmith, Zachary K., and Hammes-Schiffer, Sharon. Theoretical Study of C–H Bond Cleavage via Concerted Proton-Coupled Electron Transfer in Fluorenyl-Benzoates. United States: N. p., 2018. Web. doi:10.1021/jacs.8b10461.
Sayfutyarova, Elvira R., Goldsmith, Zachary K., & Hammes-Schiffer, Sharon. Theoretical Study of C–H Bond Cleavage via Concerted Proton-Coupled Electron Transfer in Fluorenyl-Benzoates. United States. doi:10.1021/jacs.8b10461.
Sayfutyarova, Elvira R., Goldsmith, Zachary K., and Hammes-Schiffer, Sharon. Thu . "Theoretical Study of C–H Bond Cleavage via Concerted Proton-Coupled Electron Transfer in Fluorenyl-Benzoates". United States. doi:10.1021/jacs.8b10461. https://www.osti.gov/servlets/purl/1566592.
@article{osti_1566592,
title = {Theoretical Study of C–H Bond Cleavage via Concerted Proton-Coupled Electron Transfer in Fluorenyl-Benzoates},
author = {Sayfutyarova, Elvira R. and Goldsmith, Zachary K. and Hammes-Schiffer, Sharon},
abstractNote = {Developing new strategies to activate and cleave C–H bonds is crucial for a broad range of applications. Currently a new method for C–H bond activation using multi-site concerted proton-coupled electron transfer (PCET) involving intermolecular electron transfer to an oxidant coupled to intramolecular proton transfer was reported. For a series of oxidants reacting with 2-(9H-fluoren-9-yl)benzoate, experimental studies revealed an atypical Brønsted α, defined as the slope of the logarithm of the PCET rate constant versus the logarithm of the equilibrium constant or the scaled driving force. Herein this reaction is modeled with a vibronically nonadiabatic PCET theory. Hydrogen tunneling, thermal sampling of the proton donor–acceptor mode, solute and solvent reorganization, and contributions from excited vibronic states are found to play important roles. The calculations qualitatively reproduce the experimental observation of a Brønsted α significantly less than 0.5 and explain this shallow slope in terms of exoergic processes between pairs of electron–proton vibronic states. These fundamental mechanistic insights may guide the design of more effective strategies for C–H bond activation and cleavage.},
doi = {10.1021/jacs.8b10461},
journal = {Journal of the American Chemical Society},
number = [46],
volume = [140],
place = {United States},
year = {2018},
month = {11}
}

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Works referencing / citing this record:

Theoretical analysis of the inverted region in photoinduced proton-coupled electron transfer
journal, January 2019

  • Goldsmith, Zachary K.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon
  • Faraday Discussions, Vol. 216
  • DOI: 10.1039/c8fd00240a