CHLORO, METHYL AND HYDRIDO IRIDIUM COMPLEXES WITH PH2CN2 AND OTHER DIAZOALKANE LIGANDS

Diazoalkane iridium complexes of the general composition trans-[IrCl(N2CRR')(PPh3)2] (6,7), trans-[IrCl(N2CRR')-(PiPr3)2] (9, 10, 14), trans-[IrCH3(N2CRR')(PiPr3)2] (16, 17) and [IrH2Cl(N2CRR')(PiPr3)2] (19-21) were prepared from trans-[IrCl(N2)-(PPh3)2], trans-[IrCl(C8H14)(PiPr3)2], trans-[IrCH3(C2H4)(PiPr3)2](15) and [IrH2Cl(PiPr3)2] by ligand displacement or addition reactions. The previously unknown methyl iridium derivative 15 was obtained almost quantitatively from trans-[IrCI(C2H4)(PiPr3)2] (13) and CH3Li in toluene/ether. The reaction of 15 with PhCHN2 gave trans-[IrCH3(N2)(PiPr3)2](18). Neither on thermal nor on photochemical treatment did the diazoalkane complexes react to give the corresponding carbene iridium compounds; instead, in most cases the dinitrogen complexes trans-[IrX(N2 )(PR 3)2] (X = Cl, CH 3) were obtained. The reaction of ethene, propene or styrene with diphenyldiazomethane led, in presence of [IrCl(C2H4)2]2 or [IrCl(C8H14)2]2 as catalyst, to the formation of 1,1-diphenylpropene, 1,1-diphenylbutene and 1,1,3-triphenylpropene, respectively, by C-C coupling, The olefin iridium derivatives, however, are less active catalytically than their rhodium counterparts.