Insertion of Unsaturated C-C Bonds into the O-H Bond of an Iridium(III)-Hydroxo Complex: Formation of Phosphorescent Emitters with an Asymmetrical β-Diketonate Ligand.

A synthetic methodology to prepare iridium(III) emitters of the class [3b+3b+3b'] with two -metalated 1-phenylisoquinolines and an asymmetrical β-diketonate has been discovered. The abstraction of the chloride ligands of the dimer [Ir(μ-Cl){κ-,-(CH-isoqui)}] (, CH-isoqui = 1-phenylisoquinoline) with AgBF in acetone and the subsequent addition of water to the resulting solution affords the water solvate mononuclear complex [Ir{κ-,-(CH-isoqui)}(HO)]BF (), which reacts with KOH to give the dihydroxo-bridged dimer [Ir(μ-OH){κ-,-(CH-isoqui)}] (). Treatment of the latter with dimethyl acetylenedicarboxylate leads to Ir{κ-,-(CH-isoqui)}{κ-,-[OC(COCH)CHC(OCH)O]} (), as a result of the -addition of the O-H bond of a mononuclear [Ir(OH){κ-,-(CH-isoqui)}] fragment to the C-C triple bond of the alkyne and the coordination of one of the carboxylate substituents to the metal center. Complex also reacts with α,β-unsaturated ketones. The reaction with 3-(4-methylphenyl)-1-phenylprop-2-en-1-one affords Ir{κ-,-(CH-isoqui)}{κ-,-[OC(CH)CHC(-CHMe)O]} (), whereas methyl vinyl ketone gives a mixture of Ir{κ-,-(CH-isoqui)}{κ-,-[OC(CH)CHCHO]} () and Ir{κ-,-(CH-isoqui)}{κ-,-[OC(CH)CHC(CH═CH)O]} (). Complexes and are the result of the addition of the O-H bond of the mononuclear [Ir(OH){κ-,-(CH-isoqui)}] fragment to the C-C double bond of the α,β-unsaturated ketones and the coordination of the carbonyl group to the iridium center, to generate ,-chelates which lose molecular hydrogen to aromatize into the asymmetrical β-diketonate ligands. Complexes - are phosphorescent emitters in the red spectral region (599-672 nm) in doped poly(methyl methacrylate) (PMMA) film at 5 wt % at room temperature and 2-methyltetrahydrofuran at room temperature and 77 K. They display short lifetimes (0.8-2.5 μs) and quantum yields in both doped PMMA films and in 2-methyltetrahydrofuran at room temperature depending on the substituents of the β-diketonate: about 0.6-0.5 for and and ca. 0.35 for and .