Synthesis and Reactivity of Iron-Oxocyclohexadienyl Complexes toward Proton-Coupled Electron Transfer

An iron(II) complex bearing an oxocyclohexadienyl ligand is newly designed and synthesized based on computational study by density functional theory calculations. Protonation and reduction of this iron(II) complex afford an iron(I) complex bearing a π-phenol ligand with a weak O–H bond with a bond dissociation free energy of 27.8 kcal/mol. This iron(I) complex works as a proton-coupled electron transfer (PCET) reagent to react with organic molecules. PCET from the iron(I) complex to a molybdenum nitride complex also proceeds to achieve catalytic ammonia formation from dinitrogen under mild reaction conditions.