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.