Synthesis and Characterization of Iridium(V) Coordination Complexes With an N,O-Donor Organic Ligand

We have prepared and fully characterized two isomers of [Ir^IV(dpyp)₂] (dpyp=meso-2,4-di(2-pyridinyl)-2,4-pentanediolate). These complexes can cleanly oxidize to [Ir^V(dpyp)₂]⁺, which to our knowledge represent the first mononuclear coordination complexes of Ir^V in an N,O-donor environment. One isomer has been fully characterized in the Ir^V state, including by X-ray crystallography, XPS, and DFT calculations, all of which confirm metal-centered oxidation. The unprecedented stability of these Ir^V complexes is ascribed to the exceptional donor strength of the ligands, their resistance to oxidative degradation, and the presence of four highly donor alkoxide groups in a plane, which breaks the degeneracy of the d-orbitals and favors oxidation.