Mechanistic and kinetic studies of visible light photoredox reactions

The use of visible light to enable small molecule synthesis has grown substantially over the last 15 years. While much of the focus has been on the development of new methods, mechanistic and kinetic studies can provide valuable information about reaction steps and highlight directions for optimization and new methods. This review focuses on reports of visible light, homogenous photoredox reactions that emphasize direct observation of reaction intermediates and/or contain a significant focus on mechanistic and kinetic studies. How these types of studies can improve reaction yields and rates are highlighted. Finally, reaction quantum yields for over 200 photoredox reactions are summarized for the first time. This often-neglected reaction parameter provides valuable insights into the efficiency of photoredox reactions as well as the clues to the underlying mechanism.