Cyclometalated IrIII Complex Possessing Chiral MIC ligand: Regiospecific sp3 C–H Activation and Asymmetric Transfer Hydrogenation of Ketone

Cyclometalation offers a wide number of organometallic metallacycles showing diverse applications. However, such NHC complexes synthesized via an sp³ C−H bond activation are rare. An iridium(III) complex with a chiral mesoionic N‐heterocyclic carbene (MIC) ligand, where the Ir^III forms an additional Ir−C bond via a regiospecific sp³ C−H bond activation at the N‐methylbenzyl wingtip, was synthesized and characterized. To our best knowledge, this represents the first example of cyclometalated iridium(III) complex possessing a chiral MIC donor ligand. The formation of the complex was followed by 2D correlation NMR spectroscopy and the molecular formula mass was evidenced by ESI‐HRMS mass spectrometry. The molecular structure of the Ir^III‐MIC complex was unambiguously established by the single crystal XRD data. This cyclometalated Ir^III complex was employed in the asymmetric transfer hydrogenation of 4‐bromoacetophenone, and the complex was successful to transfer chirality to the final alcohol molecules (up to 92 % ee).