Alkynes and Diynes as Precursors for Organoiridium Complexes Containing Iridium−Carbon Single and Double Bonds^,1

Abstract

The in situ generated species [IrCl(C8H14)(PiPr3)2] as well as the dihydrido complex [IrH2Cl(PiPr3)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)(PiPr3)2] with Me3SiC⋮CR (R = Ph, Me, nBu, SiMe3, CH2OH, CMe2OSiMe3, CO2Et) led to trans-[IrCl{CC(SiMe3)R}(PiPr3)2] (3−9) for R = CO2Et via the isolated π-alkyne metal intermediate trans-[IrCl(η2-Me3SiC⋮CR)(PiPr3)2] (2), photolysis of 15 in the presence of Me3SiC⋮CC⋮CSiMe3 gave trans-[IrCl{CC(SiMe3)C⋮CSiMe3}(PiPr3)2] (19). Compound 19 was also obtained by thermal or photochemical rearrangement of trans-[IrCl(η2-Me3SiC⋮CC⋮CSiMe3)(PiPr3)2] (18). The dihydrido complex 15 reacted with HC⋮CC⋮CH at −60 °C to yield [{IrHCl(PiPr3)2}2(μ-C⋮CC⋮C)] (16) and with HC⋮CC⋮CSiMe3 to give [IrHCl(C⋮CC⋮CSiMe3)(PiPr3)2] (20), from which the vinylidene isomer trans-[IrCl(CCHC⋮CSiMe3)(PiPr3)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 hydrido complex [IrHCl{C⋮CC(iPr)CMe2}(PiPr3)2] (23) was formed, the six-coordinate carbonyl hydrido vinyl derivative [IrHCl{(E)-CHCHPh}(CO)(PiPr3)2] (25) was isolated for R = H and R‘ = Ph. Treatment of 15 with HC⋮CCPh2OH afforded, via [IrHCl(C⋮CCPh2OH)(PiPr3)2] (27) or the isomer trans-[IrCl(CCHCPh2OH)(PiPr3)2] (28), the allenylideneiridium(I) compound trans-[IrCl(CCCPh2)(PiPr3)2] (29) in excellent yield. Hydrogenation of 29 gave the allene complex trans-[IrCl(η2-CH2CCPh2)(PiPr3)2] (30), the structure of which was determined by X-ray crystallography. The substituted vinylideneiridium compound trans-[IrCl{CC(SiMe3)C⋮CCPh2OH}(PiPr3)2] (33) was obtained from [IrCl(C8H14)(PiPr3)2] and Me3SiC⋮CC⋮CCPh2OH via the isomeric π-alkyne complex 32 as isolated intermediate.

Closing the Gap between MC3 and MC5 Metallacumulenes: The Chemistry of the First Structurally Characterized Transition-Metal Complex with MdCdCdCdCR2 as the Molecular Unit

“…However, in contrast to the reaction of the iridium allenylidene with CO which yields trans-[IrCl(CO)(PiPr 3 ) 2 ], [11] treatment of 8 with CO gives the 1:1 adduct 9 (Scheme 3). The presence of both the IrÀCO and the intact IrCCCCPh 2 bond in 9 is shown by the appearance of two strong bands in the IR spectrum at 1944 (n(CO)) and 1987 cm À1 (n(CCCC)), the latter being only slightly shifted to lower wavenumbers compared to that in 8.…”

“…The vinylidene complex 6 is a red-violet, only slightly air-sensitive solid, the NMR spectroscopic data of which are quite similar to those of trans-[IrCl{CCHCPh 2 (OH)}(PiPr 3 ) 2 ]. [11] The IR spectrum of 6 shows a strong band at 1654 cm À1 assigned to the C O stretching mode of the ketone functionality.…”

“…[10] The 13 C NMR spectrum of 2 displays two signals at d 109.2 and 102.0, which are slightly shifted downfield compared with those of the related complex trans-[IrCl(h 2 -Me 3 SiC CCO 2 Et)(PiPr 3 ) 2 ]. [11] Attempts to transform 2 either thermally or photochemically to the vinylidene isomer trans-[IrCl-{CC(SiMe 3 )C(O)CHPh 2 }(PiPr 3 ) 2 ] (assumed to be a potential precursor for the preparation of 8) failed.…”

“…L PiPr 3 . the hydride signal at d À 40.96, which is at a position similar to that for [IrHCl{CCC(iPr)CMe 2 }(PiPr 3 ) 2 ]. [11] While this compound is completely inert, 4 rearranges in benzene at room temperature rather quickly to the vinylidene isomer 6. This reaction can be prevented upon addition of pyridine to a solution of 4 which leads to the formation of the octahedral 1:1 adduct 5.…”

Iridium(I)- und Iridium(III)-Komplexe mit Triisopropylarsan als Ligand

“…In den letzten Jahren haben wir in einer Reihe von Arbeiten gezeigt, dass das Moleku È lfragment [IrCl(PiPr 3 ) 2 ] ein ausgezeichnetes ¹Stu È tzkorsettª fu È r die Koordination so unterschiedlicher Liganden wie C 2 H 2 [1], C 2 H 4 [2], CPh 2 [3], C=CR 2 [4], C=C=CPh 2 [5], C=C=C=CPh 2 [6], C=C=C=C=CPh 2 [7] und N 2 [8] ist. Wir hatten in ju È ngster Zeit ebenfalls darauf hingewiesen, dass es Unterschiede in der Koordinationsfa È higkeit von PiPr 3 und SbiPr 3 In Abb.…”