Half-Sandwich Iron Complexes: From Organometallic Reactivity to Catalyst Design

Half-sandwich iron complexes have long provided a versatile platform for organometallic chemistry, yet their potential as earth-abundant catalysts with deliberately engineered reactivity is only beginning to emerge. This review examines how the reactivity of the half-sandwich framework has evolved from classical stoichiometric iron chemistry towards catalytic systems in which ligand design and ligand cooperativity play increasingly active roles. Selected studies illustrate how the iron center can encode stereochemical information, how ligand frameworks can participate directly in substrate activation and how ligand structure can redirect competing reaction pathways. These examples highlight the modularity of half-sandwich iron complexes as a platform for earth-abundant iron catalysis design and suggest broader opportunities to control their reactivity through deliberate modification of the metal–ligand environment.