Proton-coupled electron transfer

A Proton-coupled electron transfer (PCET) is a chemical reaction that involves the transfer of electrons and protons from one atom to another. The term was originally coined for single proton, single electron processes that are concerted,[1] but the definition has relaxed to include many related processes. Reactions that involve the concerted shift of a single electron and a single proton are often called Concerted Proton-Electron Transfer or CPET.[2][3][4][5]

In PCET, the proton and the electron (i) start from different orbitals and (ii) are transferred to different atomic orbitals. They transfer in a concerted elementary step. CPET contrast to step-wise mechanisms in which the electron and proton are transferred sequentially.[6]

ET
[HX] + [M] → [HX]+ + [M]−
PT
[HX] + [M] → [X]− + [HM]+
CPET
[HX] + [M] → [X] + [HM]
  1. ^ Huynh, My Hang V.; Meyer, Thomas J. (2007). "Proton-Coupled Electron Transfer". Chemical Reviews. 107 (11): 5004–5064. doi:10.1021/cr0500030. PMC 3449329. PMID 17999556.
  2. ^ Warren, J. J.; Tronic, T. A.; Mayer, J. M. (2010). "Thermochemistry of Proton-Coupled Electron Transfer Reagents and Its Implications". Chemical Reviews. 110 (12): 6961–7001. doi:10.1021/cr100085k. PMC 3006073. PMID 20925411.
  3. ^ Weinberg, David R.; Gagliardi, Christopher J.; Hull, Jonathan F.; Murphy, Christine Fecenko; Kent, Caleb A.; Westlake, Brittany C.; Paul, Amit; Ess, Daniel H.; McCafferty, Dewey Granville; Meyer, Thomas J. (2012). "Proton-Coupled Electron Transfer". Chemical Reviews. 112 (7): 4016–4093. doi:10.1021/cr200177j. PMID 22702235.
  4. ^ Hammes-Schiffer, Sharon (2001). "Theoretical Perspectives on Proton-Coupled Electron Transfer Reactions". Accounts of Chemical Research. 34 (4): 273–281. doi:10.1021/ar9901117. PMID 11308301.
  5. ^ Hammes-Schiffer, Sharon; Soudackov, Alexander V. (2008). "Proton-Coupled Electron Transfer in Solution, Proteins, and Electrochemistry†". The Journal of Physical Chemistry B. 112 (45): 14108–14123. doi:10.1021/jp805876e. PMC 2720037. PMID 18842015.
  6. ^ In some literature, the definition of PCET has been extended to include the sequential mechanisms listed above. This confusion in the definition of PCET has led to the proposal of alternate names including electron transfer-proton transfer (ETPT), electron-proton transfer (EPT), and concerted proton-electron transfer (CPET).