Synthesis and reactivity of five- and six-coordinate hydrido(vinyl) iridium(III) complexes

The five-coordinate hydrido(vinyl) iridium(III) complexes [IrH(Cl){(E)-C(R)CH(CO2Me)}(PiPr3)2] (6, 7) were prepared either from [IrH2(Cl)(PiPr3)2] and RCC(CO2Me), via insertion of the alkyne into one of the IrH bonds or by careful hydrogenation of the alkyne iridium(I) derivatives trans-[IrCl{RCC(CO2Me)}(PiPr3)2]. UV irradiation of 6 (R = CO2Me) affords the isomer 3 having the vinyl ligand coordinated in a bidentate fashion.