ironcatalyzed

Iron-catalyzed refers to chemical transformations in which iron serves as the catalyst to accelerate a reaction. Iron catalysts can be homogeneous, consisting of iron complexes dissolved in solvent, or heterogeneous, supported on solids. Iron is abundant, inexpensive, and relatively low in toxicity compared with many other transition metals, which makes iron catalysis attractive for sustainable chemistry.

Iron exhibits multiple oxidation states (Fe0 to Fe3+) and can engage in single-electron transfer processes, enabling both polar and radical pathways. This redox flexibility allows a wide range of transformations but can also complicate control of selectivity. Catalyst design—such as iron complexes with porphyrin, N-heterocyclic carbene, phosphine, or pincer ligands—and the use of suitable activators or co-catalysts are important for stabilizing active species and tuning reactivity.

Representative areas of iron-catalyzed chemistry include carbon–carbon bond formation through cross-coupling and related processes, hydrogenation and transfer hydrogenation of unsaturated substrates, and hydrofunctionalization of alkenes and arenes (for example hydroboration, hydrosilylation, and hydroamination). Iron catalysts also enable various oxidation reactions, including aerobic oxidations with molecular oxygen or peroxides, and have found use in polymerization and copolymerization processes, such as olefin and cyclic ester polymerization.

Advantages of iron catalysis include abundance, low cost, and generally lower toxicity relative to many noble metals. Limitations can involve air or moisture sensitivity of some catalysts, variable turnover numbers, and sometimes more complex optimization to achieve high selectivity. Ongoing research seeks to broaden substrate scope, improve robustness, and develop practical, scalable iron-catalyzed methods.