Facile and Reversible O−H and C−H Activation by a Chiral Iridium(I) Complex

Abstract

The reactivity of the dinuclear Ir(I) complexes cis- and trans-[Ir2(μ-Cl)2((R)-(S)-PPFPPh2)2] (1, (R)-(S)-PPFPPh2 = (R)-1-{(S)-2-(diphenylphosphino)ferrocenyl}ethyldiphenylphosphine) toward O−H and C−H bonds has been studied (1 was previously shown to be a catalyst precursor for the asymmetric addition of aniline to norbornene, via N−H activation). Compound 1 undergoes clean oxidative addition of water in toluene, affording a mixture of two isomeric, dinuclear hydroxo-bridged Ir(III) complexes. Isomerization to a single product, syn-trans-[((R)-(S)-PPFPPh2)2Ir2Cl2(H)2(μ-OH)2] (3), takes place upon dissolution in THF. syn-trans-3 has been characterized by X-ray diffraction. Reaction of 1 with 2,6-dimethylaniline affords the corresponding sp3 C−H activation product 5, the crystal structure of which has been determined. Both oxidative addition reactions are (partly) reversible at high temperature.