β-Elimination-Immune PC_carbeneP Iridium Complexes via Double C–H Activation: Ligand–Metal Cooperation in Hydrogen Activation

The synthesis of two members of a new PCP pincer ligand family and their complexation with iridium has been developed. Double C–H activation results in a ligand anchored by a carbene donor; hydrogen reversibly adds to the (PC_carbeneP)­IrCl complexes 3^R (R = ⁱPr, ^tBu). Aryl, amido, and phenoxy derivatives are available from the chlorides via salt metathesis. These compounds add H₂ and eliminate H–X; the iridium compound is trapped as a PC_alkylP iridium polyhydride.