Partial Deoxygenative CO Homocoupling by a Diiron Complex

• Published in: Angewandte Chemie 2023-10, Vol.135 (41)
• Main Authors: Singh, Devender, Knight, Brian J., Catalano, Vincent J., García‐Serres, Ricardo, Maurel, Vincent, Mouesca, Jean‐Marie, Murray, Leslie J.
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Carbon dioxide; Carbon monoxide; Catalysis; Chemistry; Climate change; Coupling (molecular); Cyclophane; Deoxygenation; Fuels; Ligands; Liquid fuels; Metal ions; Spectroscopy
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202308813

One 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 Fe 2 (CO) 2 L ( 2 ), where L 2− is a bis(β‐diketiminate) cyclophane, gives [K(THF) 5 ][Fe 2 (CO) 2 L ] ( 3 ), which undergoes silylation to Fe 2 (CO)(COSiMe 3 ) L ( 4 ). Subsequent C‐OSiMe 3 bond cleavage and C=C bond formation occurs upon reduction of 4 , yielding Fe 2 (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 KEt 3 BH or methanol releases the C 2 O 2− ligand with retention of the diiron core