Copper(I) Photoredox Catalysts Bearing Tetradentate Phenanthroline-Based Ligands: Understanding the Interplay between Structure and Function

Phenanthroline-based copper(I) complexes represent some of the earliest reported photoredox catalysts. Many of these species exhibit poor coordinative stability and are prone to disproportionate in solution, which can affect catalyst turnover and viability. This may also complicate the elucidation of reaction mechanisms. In this study, the fundamental properties of a library of copper(I) complexes that constitute six general classes of tetradentate, phenanthroline-based supporting ligands bearing covalently tethered neutral donor groups (e.g., phosphine, phosphinite, phosphite, oxazoline or pyrazole moieties) were investigated. These systems were employed to explore the relationship between structure and function in copper(I) photoredox catalysis.