Recent Advances in Photoactive First‐Row Transition Metal Complexes for Organic Synthesis

Comprehensive Summary Over the past few decades, first‐row transition metal complexes have emerged as promising candidates for photocatalyst design. By strategically selecting ligands and optimizing their structures and configurations, researchers have developed a range of photoactive complexes of copper, nickel, iron, cobalt, chromium, and manganese, which exhibit distinct photoactivity compared to conventional heavy metal complexes and organic dyes. Despite these advances, their application in organic synthesis remains in its early stages. This comprehensive review endeavors to trace the evolution of photoactive first‐row transition metal complexes, with a particular focus on Cr, Mn, Co, and Fe systems as triplet‐state photosensitizers and/or photoredox catalysts in organic transformations. Through a detailed analysis of design principles, reaction mechanisms, and synthetic utility, we highlight both the transformative potential and current limitations of these cost‐effective, Earth‐abundant metal complexes in photocatalysis.