28195-56-4Relevant academic research and scientific papers
Crystal Structure of the Quasitetrahedral Iridium(I) Complex, Ir(COCH2CMe3)2. An Intermediate in Cyclotrimerization of Activated Alkynes by 16-Electron Alkyl Complexes of Iridium, trans-RIr(CO)L2 (R=Me, CH2CMe3; L=PPh3, P(p-tolyl)3)
Rappoli, Brian J.,Churchill, Melvin Rowen,Janik, Thomas S.,Rees, Wayne M.,Atwood, Jim D.
, p. 5145 - 5149 (1987)
Complexes trans-RIr(CO)L2 (R=Me, CH2CMe3; L=PPh3 or P(p-tolyl)3) are cyclotrimerization catalysts for activated acetylenes.Stoichiometric reaction between C2(CO2Me)2 and trans-Me3CCH2Ir(CO)2 results in the formation of Ir(COCH2CMe3)2,an unusual tetrahedral, 16-electron, iridium(I) complex.An X-ray diffraction study confirms the geometry.The complex Ir(COCH2CMe3)2 crystallizes in the centrosymmetric monoclinic space group P21/c with a=11.125 (2) Angstroem, b=21.725 (6) Angstroem, c=20.889 (5) Angstroem, β=93.465 (16)deg, V=5039 (2) Angstroem3, and Z=4.Single-crystal X-ray difraction data (Mo Kα, 2θ=5-45deg) were collected and the structure solved and refined to RF=6.2percent for those 5196 data with (F0) >3?((F0)) F=5.0percent for 4433 data with (F0 >6?((F0))>.If we regard the η2-C2(CO2Me)2 ligand as occupying a single stereochemical site (as is usually the case) the molecule is a tetrahedral complex of Ir(I) in which Ir-P=2.334 (3) and 2.314 (3) Angstroem, the Ir-C(acyl) bond length is 1.951 (13) Angstroem, and Ir...cent (center of acetylenic linkage) =1.941 Angstroem.Interligand angles are P(1)-Ir-P(2)=105.20 (10)deg, P(1)-Ir-C(acyl)=94.20 (36)deg, P(1)-Ir-cent =122.80deg, P(2)-Ir-C(acyl)=91.86 (36)deg, P(2)-Ir-cent =123.28deg, and C(acyl)-Ir-cent =111.15deg.The mechanism of the cyclotrimerization reaction involves coordination of an acetylene molecule, an alkyl migration, coordination of a second acetylene molecule, metallacyclopentadiene formation, and cycloaddition of a third acetylene molecule leading to elimination of the derived benzenoid cyclotrimer.
Selective hydroboration of equilibrating allylic azides
Liu, Ruzhang,Zhang, Yuanyuan,Xu, Jun
supporting information, p. 8913 - 8916 (2021/09/13)
The iridium(i)-catalyzed hydroboration of equilibrating allylic azides is reported to provide only the anti-Markovnikov product of alk-1-ene isomers in good yields and with good functional group tolerance.
Bond-forming reactions to a coordinated hydroxo group: Reaction of trans-Ir(CO)(OH)(P(p-tolyl)3)2 with MeI, EtI, HCl, CH3C(O)Cl, and H2
Thompson, Jeffrey S.,Randall, Sherri L.,Atwood, Jim D.
, p. 3906 - 3910 (2008/10/08)
Reactions of trans-Ir(CO)(OH)(P(p-tolyl)3)2 with MeI, EtI, HCl, and CH3C(O)Cl lead to the formation of bonds between the hydroxide and the adding group. For MeI and EtI addition, where the alcohols are formed, the reactions occur by oxidative addition followed by reductive elimination to form the carbon-oxygen bond. Reaction with HCl proceeds very rapidly by protonation of the hydroxide to eliminate H2O. The reaction of trans-Ir(CO)(OH)(P(p-tolyl)3)2 with acetyl chloride gives a mixture of products from initial attack of acetyl chloride on the hydroxide to produce acetic acid. Subsequent oxidative addition of the acid produces an acetate complex. Reaction of trans-Ir(CO)(OH)(P(p-tolyl)3)2 with H2 produces the trihydride H3Ir(CO)(P(p-tolyl)3)2 and H2O. This reaction is partially reversible; treatment of the trihydride with H2O produces the hydroxy complex. The reactions reported here are among the first that exhibit bond formation to a metal-bound hydroxo group.
Formation of carbon-carbon bonds by oxidative-addition reactions to trans-MeIr(CO)(P(p-tolyl)3)2
Thompson, Jeffrey S.,Atwood, Jim D.
, p. 3525 - 3529 (2008/10/08)
Oxidative addition of various organic halides to trans-Ir(CO)(Me)(P(p-tolyl)3)2 has been examined by variable-temperature NMR spectroscopy. For PhCH2Cl, CH3C(O)Cl, Ph2CHC(O)Cl, PhC(O)Cl, and PhCH2C(O)Cl oxidative addition is followed by reductive elimination to form carbon-carbon bonds. For reaction of trans-Ir(CO)(Me)(P(p-tolyl)3)2 with CH3C(O)Cl the intermediate is characterized by 1H and 31P NMR spectroscopy at -5°; acetone elimination is significant at 10°C. For the other complexes the oxidative addition is sufficiently slow that an intermediate cannot be identified. Oxidative addition of MeI and EtI to trans-MeIr(CO)(P(p-tolyl)3)2 leads to complexes Ir(CO)(I)(R)(Me)(P(p-tolyl)3)2 that are characterized by 1H and 31P NMR spectroscopy. For R = Me this complex is stable; for R = Et the complex slowly undergoes β-elimination leading to C2H4 and CH4. These results provide strong support for a mechanism involving halide dissociation from the iridium(III) complexes.
Silicon-oxygen bond-forming reactions upon addition of silanes and silyl halides to the 16-electron alkoxyiridium complexes trans-ROIr(CO)[P(p-tol)3]2 (R = Me or Ph; p-tol = p-Tolyl). Crystal and molecular structure of H2Ir(CO)(SiMe2Ph)[P(p-tol)3]2
Rappoli, Brian J.,Janik, Thomas S.,Churchill, Melvyn Rowen,Thompson, Jeffrey S.,Atwood, Jim D.
, p. 1939 - 1944 (2008/10/08)
The reactions of silanes and silyl halides with the 16-electron alkoxyiridium complexes trans-ROIr(CO)[P(p-tol)3]2 (R = Me or Ph; p-tol = p-tolyl) are reported. The silanes add oxidatively to the alkoxyiridium complex; the resulting complex undergoes reductive elimination of an alkoxysilane with ultimate formation of H2Ir(CO)(SiR3)[P(p-tol)3]2. Reactions of silyl halides with the alkoxy complex results in formation of silicon-oxygen bonds. The dihydride H2Ir(CO)(SiMe2Ph)[P(p-tol)3]2, which is an active hydrogenation catalyst, was subjected to structural analysis. It crystallizes in the centrosymmetric triclinic space group P1 with a = 10.692 (1) ?, b = 11.199 (2) ?, c = 20.557 (4) ?, α = 75.991 (14)°, β = 84.505 (14)°, γ = 77.503 (11)°, V = 2329 (1) ?3, and Z = 2. Diffraction data (Mo Kα, 2θ = 4.5-45.0°) were collected with a Syntex P21 automated diffractometer; the structure was solved and refined to RF = 4.9% for all 6119 reflections (RF = 3.6% for those 5094 data with |Fo| > 6σ(|Fo|)). The non-hydride ligands occupy expanded sites in an octahedral iridium(III) complex with Ir-P(1) = Ir-P(2) = 2.366 (2) ?, Ir-Si = 2.414 (2) ?, and Ir-CO = 1.900 (8) ?. The SiMe2Ph ligand is trans to a P(p-tol)3 ligand (P(1)-Ir-Si = 146.39 (7)°). The hydride ligands were located and refined; their positions are of limited accuracy, but they lie in mutually cis sites, trans to a P(p-tol)3 ligand (P(2)-Ir-H(1) = 169.2 (21)°) and to the CO ligand (C-(1)-Ir-H(2) = 169.4 (22)°).
