η -Arene Complexes as Intermediates in the Preparation of Molecular Phosphorescent Iridium(III) Complexes.

Molecular phosphorescent heteroleptic bis-tridentate iridium(III) emitters have been prepared via η -arene intermediates. In the presence of 4.0 mol of AgOTf, the complex [(IrCl{κ -N,C,N-(pyC HMe py)})(μ-Cl)] (1; pyC H Me py=1,3-di(2-pyridyl)-4,6-dimethylbenzene) reacted with 9-(6-phenylpyridin-2-yl)-9H-carbazole (PhpyCzH) and 2-phenoxy-6-phenylpyridine (PhpyOPh) to give [Ir{κ -N,C,N-(pyC HMe py)}{κ -C,N,C'-(C H pyCzH)}]OTf (2) and [Ir{κ -N,C,N-(pyC HMe py)}{κ -C,N,C'-(C H pyOPh)}]OTf (3). The X-ray diffraction structures of 2 and 3 reveal that the carbazolyl and phenoxy substituents of the C,N,C' ligand coordinate to the metal center to form an η -arene π bond. Treatment of 2 and 3 with KOtBu led to the deprotonation of the coordinated carbon atom of the η -arene group to afford the molecular phosphorescent [5t+4t'] heteroleptic iridium(III) complexes [Ir{κ -N,C,N-(pyC HMe py)}{κ -C,N,C'-(C H pyCz)}] (4) and [Ir{κ -N,C,N-(pyC HMe py)}{κ -C,N,C'-(C H pyOC H )}] (5). These complexes are green emitters that display short lifetimes and high quantum yields of 0.73 (4) and 0.87 (5) in the solid state.