Self-Assembly of the Co-Catalysts of a Dual Photoredox/Hydrogen Atom Transfer Catalytic Process: Curiosity or Opportunity?

Dual photoredox/Hydrogen atom transfer (HAT) catalytic processes are an emerging class of redox neutral catalytic processes which allow the functionalization of inert C(sp³)−H bonds. A key step of such processes is a single electron transfer (SET) between the photoredox catalyst (PC) excited state and the HAT catalyst, which is typically a chloride or a bromide ion. Until recently, the SET has only been considered as an intermolecular process. Considering recent works dealing with the photooxidation of halides into halogen atoms occurring within Ru-based PC ⋅ halides complexes, as well as recent results from our group describing a prototypical example of an organic PC ⋅ chloride complex applied to the photoalkylation of C(sp³)−H bonds, this concept article aims at discussing the potential benefits and drawbacks of self-assembling the co-catalysts employed in dual photoredox/HAT catalytic processes.