Iridium Complexes Containing a PNP Pincer Ligand: Syntheses, Structural Chemistry, and Bond Activations

The coordination chemistry of the monoanionic PNP pincer ligand 3,6‐di‐ tert ‐butyl‐1,8‐bis[(diphenylphosphanyl)methyl]carbazole (Cbzdiphos) was investigated for different iridium(I) and iridium(III) complexes. Reaction of the protio ligand with [Ir(acac)(cod)] (acac = acetylacetonate; cod = 1,5‐cyclooctadienyl) gave [(Cbzdiphos)Ir(cod)] ( 1 ). Upon hydrogenation the dihydrido complex [(Cbzdiphos)IrH 2 ] ( 2 ) was obtained, and its reactivity in different organometallic transformations was examined. Treating 2 with ammonia afforded [(Cbzdiphos)IrH 2 (NH 3 )] ( 3 ), whereas treatment with diphenylacetylene (dpa) yielded the Ir I compound [(Cbzdiphos)Ir(dpa)] ( 4 ) and trans ‐stilbene. Furthermore, the conversion with norbornene led to a reactive species, which activated C–H and C–Cl bonds. The reaction with THF gave a Fischer carbene [(Cbzdiphos)Ir{=C(OC 3 H 6 )}] ( 8 ) after double C–H bond activation, whereas treatment with benzene or chlorobenzene afforded the oxidative addition products [(Cbzdiphos)Ir(Ph)H] ( 5 ) and [(Cbzdiphos)Ir(Ph)Cl] ( 7 ).