Room-temperature C–H activation of the phosphino-ketone Ph2PCH2C(O)Ph leading to an iridium(III) complex with a hybrid phosphino-enolate ligand

The reaction of [Ir(cod)(μ-Cl)]2 (cod = 1,5-cyclooctadiene) with 2 equiv of the ketophosphine Ph2PCH2C(O)Ph in the presence of TlPF6 afforded the hydrido, phosphino-enolate Ir(III) complex [IrH(cod){Ph2PCH···C(···O)Ph,κP,κO}{Ph2PCH2C(O)Ph,κP}]PF6 (4), which results from the room temperature activation of a C–H bond from the PCH2 moiety. The distorted octahedral coordination environment around the metal centre in 4 contains the cod ligand, the P atom of the monodentate ketophosphine and the P,O donor atoms of a chelating phosphino-enolate ligand acting as a 3-electron donor. The hydride ligand was located on the difference Fourier map obtained by single-crystal X-ray diffraction studies and is trans to the enolate oxygen and cis to the two, mutually cis P atoms. The reaction of this complex with NaH in THF led to the isolation of the Ir(I) complex [Ir(cod){Ph2PCH···C(···O)Ph,κP,κO}{Ph2PCH2C(O)Ph,κP}] (5). The penta-coordination environment around the metal centre in 5 includes the cod ligand, one 3-electron donor P,O chelating phosphino-enolate ligand and a P-bound Ph2PCH2C(O)Ph ligand containing an uncoordinated ketone function. The structures of 4·CH2Cl2 and 5·C7H8 have been determined by X-ray diffraction analysis.