Iridium Abnormal N-Heterocyclic Carbene Hydrides via Highly Selective C−H Activation

Imidazoliums with proximal phosphines undergo C−H oxidative addition on [Ir(COD)Cl]₂ to give iridium(III) abnormal carbene hydrides. The effects of the length of the linker between the imidazolium and the phosphine are systematically studied. These C−H activation products can undergo base-promoted H−Cl reductive elimination to afford the corresponding Ir(I) abnormal NHC complexes.