Ir(tri-N-Heterocyclic Carbene)-Catalyzed Production of Hydrogen and C_n Acids from Ethylene Glycol

Novel tri-N-heterocyclic carbene (triNHC)-coordinated iridium catalysts (Ir(triNHC)) were employed for generating clean hydrogen and useful Cn acids from biomass-derived alcohols. The high efficiency and fast rate of hydrogen production (maximum turnover frequency = 13,080 h-1 and 485 L of H2/gcat center dot h) from sustainable ethylene glycol were elucidated by the increased electron-richness of Ir(triNHC) complexes where three NHC ligands were coordinated to an iridium(I) ion. Elaborated mechanistic studies support the proposed reaction mechanisms forming H2 and Cn acids. This Ir(triNHC)-catalyzed process converting sustainable alcohols to useful fuels and chemicals is a promising carbon-neutral process.