Solvent promoted reversible cyclometalation in a tethered NHC iridium complex

Abstract

Reaction of [Ir(COD)(py–I^tBu)]⁺ (py–I^tBu = 3-tert-butyl-1-picolylimidazol-2-ylidene) with acetonitrile results in reversible intramolecular C–H bond activation of the NHC ligand and formation of [Ir(η²:η¹-C₈H₁₃)(py–I^tBu′)(NCMe)]⁺. Coordinated COD acts as an internal hydride acceptor and acetonitrile coordination offsets the otherwise unfavourable thermodynamics of the process.