Concerted proton-electron transfers: fundamentals and recent developments.

Area of Science:

• Physical Chemistry
• Chemical Kinetics
• Electrochemistry

Background:

• Proton-coupled electron transfers (PCET) are fundamental in numerous natural and synthetic chemical processes.
• Understanding the mechanisms of PCET is crucial for developing efficient catalytic systems and artificial photosynthesis.

Purpose of the Study:

• To review and analyze concerted proton-electron transfer (CPET) reactions, where electron and proton transfers occur simultaneously.
• To elucidate the kinetic characteristics of CPET reactions using semiclassical models.
• To explore the role of the proton acceptor, particularly water, in CPET processes.

Main Methods:

• Application of semiclassical models for kinetic characterization of CPET reactions.
• Analysis of activation versus driving force relationships.
• Investigation using stopped-flow and laser flash-quench techniques for homogeneous reactions.
• Electrochemical methods for studying CPET processes.

Main Results:

• Semiclassical models provide insights into reorganization energies and kinetic isotope effects for CPET.
• Water demonstrates exceptional proton acceptor capabilities due to its hydrogen-bonding network.
• Discrimination between concerted and stepwise reaction pathways is achieved.
• Recent advancements focus on modeling CPET reactions involving heavy-atom bond cleavage.

Conclusions:

• Concerted proton-electron transfer reactions can be effectively modeled and kinetically characterized.
• Water's unique properties make it a highly effective proton acceptor in CPET.
• Further research into modeling complex CPET reactions, especially those involving bond breaking, is warranted.