Novel Intramolecular C−H Bond Activation in an Iridium dppm Complex

Reaction of TpIr(C2H4)2 (Tp = tris-pyrazolylborate) with various chelating phosphine ligands has been explored.
Reaction with bis-diphenylphosphinoethane leads to complete displacement of the Tp ligand. With bis-diphenylphosphinomethane, an intramolecular proton transfer from the methylene bridge to the iridium center occurs
to give an iridium hydride complex formally resulting from oxidative C−H bond activation. Reaction with 2,2-bis(diphenylphosphino)propane (dppip) affords an Ir(I) complex formulated as κ2-TpIr(dppip). Protonation of this Ir(I)
complex gives a six coordinate Ir(III) hydride species.