Partial Deoxygenative CO Homocoupling by a Diiron Complex

Abstract

AbstractOne route to address climate change is converting carbon dioxide to synthetic carbon‐neutral fuels. Whereas carbon dioxide to CO conversion has precedent in homo‐ and heterogeneous catalysis, deoxygenative coupling of CO to products with C−C bonds—as in liquid fuels—remains challenging. Here, we report coupling of two CO molecules by a diiron complex. Reduction of Fe2(CO)2L (2), where L2− is a bis(β‐diketiminate) cyclophane, gives [K(THF)5][Fe2(CO)2L] (3), which undergoes silylation to Fe2(CO)(COSiMe3)L (4). Subsequent C‐OSiMe3 bond cleavage and C=C bond formation occurs upon reduction of 4, yielding Fe2(μ‐CCO)L. CO derived ligands in this series mediate weak exchange interactions with the ketenylidene affording the smallest J value, with changes to local metal ion spin states and coupling schemes (ferro‐ vs. antiferromagnetism) based on DFT calculations, Mössbauer and EPR spectroscopy. Finally, reaction of 5 with KEt3BH or methanol releases the C2O2− ligand with retention of the diiron core