Bromination and C–C Cross-Coupling Reactions for the C–H Functionalization of Iridium(III) Emitters

The orthometalated phenyl groups of the dimer [Ir(μ-Cl){κ2-C,N-(C6H3Me-py)}2]2 have been selectively brominated, at para-position with regard to Ir–C bonds, N-bromosuccinimide. bromination leads [Ir(μ-Cl){κ2-C,N-(C6H2MeBr-py)}2]2, which affords mononuclear derivatives Ir{κ2-C,N-(C6H2MeBr-py)}2{κ2-O,N-[OC(O)-py]}, Ir{κ2-C,N-(C6H2MeBr-py)}2{κ2-O,O-(acac)}, and Ir{κ2-C,N-(C6H2MeBr-py)}2{κ2-C,N-[C6H4-Mepy]} by replacement chloride bridges a picolinate anion, an acac group, 2-phenyl-5-methylpyridine ligand, respectively. Complexes Ir{κ2-C,N-(C6H2MeBr-py)}2{κ2-O,O-(acac)} subsequently postfunctionalized means palladium-catalyzed Suzuki–Miyaura cross-coupling give Ir{κ2-C,N-(C6H2MeR-py)}2{κ2-O,O-(acac)} (R = Me, Ph) Ir{κ2-C,N-(C6H2Me2-py)}2{κ2-C,N-[C6H4-Mepy]}. These [3b + 3b 3b′] compounds are green-yellow emitters (488–580 nm) upon photoexcitation, in doped poly(methyl methacrylate) (PMMA) film 5 wt % room temperature 2-methyltetrahydrofuran (2-MeTHF) 77 K. They display lifetimes range 1.0–5.0 μs quantum yields PMMA films 2-MeTHF between 0.84 0.40.