Base-Promoted, Remote C–H Activation at a Cationic (η5‑C5Me5)Ir(III) Center Involving Reversible C–C Bond Formation of Bound C5Me5

C–H bond activation at cationic [(η5-C5Me5)­Ir­(PMe2Ar′)] centers is described, where PMe2Ar′ are the terphenyl phosphine ligands PMe2ArXyl2 and PMe2ArDipp2. Different pathways are defined for the conversion of the five-coordinate complexes [(η5-C5Me5)­IrCl­(PMe2Ar′)]+, 2­(Xyl)+ and 2­(Dipp)+, into the corresponding pseudoallyls 3­(Xyl)+ and 3­(Dipp)+. In the absence of an external Brønsted base, electrophilic, remote ζ C–H activation takes place, for which the participation of dicationic species, [(η5-C5Me5)­Ir­(PMe2Ar′)]2+, is proposed. When NEt3 is present, the PMe2ArDipp2 system is shown to proceed via 4­(Dipp)+ as an intermediate en route to the thermodynamic, isomeric product 3­(Dipp)+. This complex interconversion involves a non-innocent C5Me5 ligand, which participates in C–H and C–C bond formation and cleavage. Remarkably, the conversion of 4­(Dipp)+ to 3­(Dipp)+ also proceeds in the solid state.