Chromium in Visible‐Light Photocatalysis: Unique Reactivity, Mechanisms and Future Directions

Abstract Visible‐light photocatalysis has emerged as a prominent research area in modern organic synthesis and environmental science. As an important transition metal, chromium has garnered widespread attention in the field of visible‐light photocatalysis in recent years, primarily manifested in the following aspects: a) the unique photochemical properties of chromium(III) complexes endow them with longer excited‐state lifetimes and higher reactivities under certain conditions; b) by harnessing visible light to induce single‐electron transfer or hydrogen atom transfer to generate radicals, which subsequently form alkyl‐chromium(III) intermediates with chromium(II) ligands, these intermediates can selectively attack electron‐deficient carbonyl compounds, enabling the construction of target products; c) following metals like cerium, copper, iron, nickel, cobalt, titanium, and bismuth, the ligand‐to‐metal charge transfer (LMCT) reaction pathways in chromium photocatalysis have also been extensively investigated. This review will provide a comprehensive summary of recent research on chromium‐mediated photocatalytic reactions, offering an in‐depth exploration of their unique reactivity, mechanisms, and future directions.