η1-arene complexes as intermediates in the preparation of molecular phosphorescent iridium(III) complexes

Abstract

Molecular phosphorescent heteroleptic bis-tridentate iridium(III) emitters have been prepared via η1-arene intermediates. In the presence of 4.0 mol of AgOTf, the complex [(IrCl{κ3-N,C,N-(pyC6HMe2py)})(μ-Cl)]2 (1; pyC6H2Me2py=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{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C′-(C6H4pyCzH)}]OTf (2) and [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C′-(C6H4pyOPh)}]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 η1-arene π bond. Treatment of 2 and 3 with KOtBu led to the deprotonation of the coordinated carbon atom of the η1-arene group to afford the molecular phosphorescent [5t+4t′] heteroleptic iridium(III) complexes [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C′-(C6H4pyCz)}] (4) and [Ir{κ3-N,C,N-(pyC6HMe2py)}{κ3-C,N,C′-(C6H4pyOC6H4)}] (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.