Formation of 5-membered metallacycles at iPrPCPIr by C–H, O–H, and C–CO bond cleavage

Cyclometalation of the 16 electron iPrPCPIr fragment (iPrPCP = κ3-2,6-C6H3(CH2P(iPr)2)2) by biphenyl, phenanthrene, fluorenone, benzophenone, and 1-naphthol is reported. Biphenyl and phenanthrene are found to undergo facile double C–H activation to form complexes (iPrPCP)Ir(κ2-2,2′-C12H8) (1) and (iPrPCP)Ir(κ2-2,2′-C14H8) (2) which are readily converted to their octahedral CO adducts 1-CO and 2-CO, respectively, by exposure to 1 atm of carbon monoxide. Complex 1-CO is also formed through the decarbonylation of fluorenone by iPrPCPIr. Reaction of iPrPCPIr with benzophenone leads to C–H activation and oxygen coordination yielding the trans-(C,H) addition species (iPrPCP)Ir(H)(κ-O,C–OC13H9) (3a) as the kinetic product. Heating of 3a induces isomerization to the trans-(O,H) orientation product 3b. Reaction of iPrPCPIr with 1-naphthol at room temperature provides the O–H addition product (iPrPCP)Ir(H)(OC10H7) (4). Heating of 4 effects cyclometalation of 1-naphthol, to form (iPrPCP)Ir(κ-O,C–OC10H6) (5) by subsequent C–H activation.

Cyclometalation of the 16 electron iPrPCPIr fragment (iPrPCP = κ3-2,6-C6H3(CH2P(iPr)2)2) by biphenyl, phenanthrene, fluorenone, benzophenone, and 1-naphthol leads to double C–H activation, decarbonylation, and cyclometallation to form metallacycles.Figure optionsDownload as PowerPoint slide