β-Elimination-Immune PCcarbeneP 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 (PCcarbeneP)-IrCl complexes 3(R) (R = Pr-i, Bu-t). Aryl, amido, and phenoxy derivatives are available from the chlorides via salt metathesis. These compounds add H-2 and eliminate H-X; the iridium compound is trapped as a PCalkylP iridium polyhydride.