On the reactivity of [IrCl(N2)(PPh3)2] with alkynylsilanes – A new route to vinylidene iridium(I) complexes

The iridium dinitrogen complex [IrCl(N2)(PPh3)2] (1) was found to react with alkynylsilanes View the MathML sourceRCCSiR3′ to form the vinylidene iridium(I) complexes trans -View the MathML source[IrCl{CCR(SiR3′)}(PPh3)2] (R/R′ = Ph/Me, 2; Me/Me, 3; Bn/Me, 4; SiMe3/Me, 5; SiEt3/Et, 6; iPr/Me, 7) and with Me3SiCtriple bond; length of mdashCC(O)R to yield the iridium η2-alkyne complexes trans-[IrCl{η2-Me3SiCtriple bond; length of mdashCC(O)R}(PPh3)2] (R = OEt, 9; Me, 11). Complex 9 was found to isomerize upon heating or upon UV irradiation yielding the vinylidene complex trans-[IrCl{double bond; length as m-dashCdouble bond; length as m-dashC(SiMe3)CO2Et}(PPh3)2] (10). The reaction of 1 with Me3SiCtriple bond; length of mdashCsingle bondCtriple bond; length of mdashCSiMe3 yielded the complex trans-[IrCl{double bond; length as m-dashCdouble bond; length as m-dashC(SiMe3)Ctriple bond; length of mdashCSiMe3}(PPh3)2] (8), whereas with MeO2CCtriple bond; length of mdashCCO2Me the iridacyclopentadiene complex [Ir{C4(CO2Me)4}Cl(PPh3)2] (13) was formed. The complexes were characterized by means of 1H, 13C and 31P NMR spectroscopy as well as by IR spectroscopy and microanalysis.