LMCT-Driven Iron Photocatalysis: Mechanistic Insights and Synthetic Applications

Iron-based photocatalysis has emerged as a sustainable and versatile platform for facilitating a wide range of chemical transformations, offering an appealing alternative to precious metal photocatalysts. Among the various activation modes, ligand-to-metal charge transfer (LMCT)-driven homolysis of Fe(III)–L(ligand) bonds has garnered considerable attention due to its ability to generate reactive radical species under mild conditions, without requiring the matching of substrates’ redox potentials. In this review, we present a comprehensive overview of recent developments in LMCT-driven iron photocatalysis, with a particular focus on both mechanistic insights and synthetic applications published in the last five years. We classify Fe(III)–L homolysis into four major categories based on the nature of the coordinated ligand: halides, carboxylates, alkoxides, and azide. For a few cases, mechanistic understanding derived from spectroscopic studies, computational modeling, and kinetic investigations is discussed in more detail. We further highlight the expanding repertoire of synthetic transformations enabled by LMCT-driven iron photocatalysis, including C–H functionalization, alkene functionalization, cross-coupling, oxidation, and radical-mediated bond formation. Finally, we provide future perspectives on the continued development of LMCT-based iron photocatalysis as a broadly applicable platform for sustainable organic synthesis. This review aims to serve as a valuable resource for researchers interested in leveraging the full potential of LMCT-mediated iron photocatalysis in modern organic chemistry.