Synthesis and Reactivity of IrIII Complexes Bearing C‑Metalated Pyrazolato Ligands

A bidentate triazolinylidene-pyrazole chelate ligand was metalated with [IrCp*Cl2]2 to give C,N-chelate complex [4]­I. The N1-metalated pyrazole subsequently underwent a rollover metalation to give the complex with C5,C4-metalated pyrazolato ligand [5]. The reactivity of [5] toward insertion and protonation was investigated. Complex [5] was found to react with CO to give IrIII carbonyl complex [6]­I, which subsequently reacted under migratory CO insertion into the Ir–C­(pyrazolato) bond to give [7]. The reaction of [5] with the terminal alkyne methyl propiolate yielded 1,2 insertion product [8], featuring a 7-membered C,C-chelate ring.