High Oxidation State Iridium Mono-μ-oxo Dimers Related to Water Oxidation Catalysis

J Am Chem Soc. 2016 Dec 14;138(49):15917-15926. doi: 10.1021/jacs.6b07716. Epub 2016 Dec 1.


The highly active iridium "blue solution" chemical and electrochemical water oxidation catalyst obtained from Cp*IrL(OH) precursors (L = 2-pyridyl-2-propanoate) has been difficult to characterize as no crystal structure can be obtained because of the multiplicity of geometrical isomers present. Other data suggest complete loss of the Cp* ligand and the formation of a LIr-O-IrL unit. We have now developed a route to a series of well-defined Ir(IV,IV) mono-μ-oxo dimers, containing the closely related L2Ir-O-IrL2 unit. Unlike the catalyst, these model compounds are separable by silica gel chromatography and readily form single crystals. We report three stereoisomers with the formula ClL2Ir-O-IrL2Cl, which are fully characterized, including by X-ray crystallography, and are compared to the "blue solution". To the best of our knowledge, these species represent the first examples of structurally characterized dinuclear μ-oxo Ir(IV,IV) compounds without metal-carbon bonds.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't