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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.
Chaudhuri et al. (Wed,) studied this question.