Alkynes and diynes as precursors for organoiridium complexes containing iridium-carbon single and double bonds

The in situ generated species [IrCl(C8H14)(PiPr(3))(2)] as well as the dihydrido complex [IrH2-Cl(PiPr(3))(2)] (15) were found to be quite reactive toward alkynes and diynes with either H or SiMe3 as substituents at the C=C and C=CC=C units. While the thermal or photochemical reaction of [IrCl(C8H14)(PiPr(3))(2)] With Me3SiC=CR (R = Ph, Me, nBu, SiMe3, CH2OH, CMe2-OSiMe3, CO2Et) led to trans-[IrCl{=C=C(SiMe3)R}(PiPr(3))(2)] (3-9) for R = CO2Et via the isolated pi-alkyne metal intermediate trans-[IrCl(eta(2)-Me3SiC=CR)(PiPr(3))(2)] (2), photolysis of 15 in the presence of Me3SiC=CC=CSiMe3 gave trans-[IrCl{=C=C(SiMe3)C=CSiMe3}(PiPr(3))(2)] (19). Compound 19 was also obtained by thermal or photochemical rearrangement of trans-[IrCl(eta(2)-Me3SiC=CC=CSiMe3)(PiPr(3))(2)] (18). The dihydrido complex 15 reacted with HC=CC=CH at -60 degrees C to yield [{IrHCl(PiPr(3))(2)}(2)(mu-C=CC=C)] (16) and with HC=CC=CSiMe3 to give [IrHCl(C=CC=CSiMe3)(PiPr(3))(2)] (20), from which the vinylidene isomer trans-[IrCl(=C=CHC=CSiMe3)(PiPr(3))(2)] (22) was generated on heating. The reaction of 15 with propargylic alcohols HC=CCR(R')OH led to different types of products, depending on the substituents R and R'. Whereas for R = R' = iPr the five-coordinate alkynyl hydride complex [IrHCl{C=CC(iPr)=CMe2}(PiPr(3))(2)] (23) was formed. the six-coordinate carbonyl hydride vinyl derivative [IrHCl{(E)-CH=CHPh}(CO)(PiPr(3))(2)] (25) was isolated for R = H and R' = Ph. Treatment of 15 with HC=CCPh2OH afforded, via [IrHCl(C=CCPh2OH)(PiPr(3))(2)] (27) or the isomer trans-[IrCl(=C=CHCPh2OH)(PiPr(3))(2)] (28), the allenylideneiridium(I) compound trans-[IrCl(=C=C=CPh2)(PiPr(3))(2)] (29) in excellent yield. Hydrogenation of 29 gave the allene complex trans-[IrCl(eta(2)-CH2=C=CPh2)(PiPr(3))(2)] (30), the structure of which was determined by X-ray crystallography. The substituted vinylideneiridium compound trans-[IrCl{=C=C(SiMe3)C=CCPh2OH}(PiPr(3))(2)] (33) was obtained from [IrCl(C8H14)(PiPr(3))(2)] and Me3SiC=CC=CCPh2OH via the isomeric pi-alkyne complex 32 as isolated intermediate.