Sigma bond metathesis iridium


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This realization led us to hypothesize that a small donor ligand may be able to bind to the metal center and associatively displace the allene. We chose carbon monoxide CO as our ligand of choice due to the strength of metal carbonyl interactions and the small, linear, nature of the ligand. Scheme 3. Promising results have been obtained with a CO promoted liberation of the allene from the iridium center.

Although we are at a very preliminary stage in our investigations, we believe this result may be the key to achieving catalytic turnover in this system as it is well-established that metal-CO interactions are susceptible to both temperature and photolysis to liberate CO and afford a coordination vacancy at the metal center Scheme 3.

Chemicals and solvents were purchased from commercial suppliers and were used as received except as follows: TBE and 1-Phenylbutyne were degassed using freeze-pump-thaw methodology. Chemical shifts are given in ppm. Coupling constants J are given in Hertz Hz. The terms m, s, d, t, q, quint. The term br means that the signal is broad. CCDC contain the supplementary crystallographic data for this paper.

Subsequently, bromoethane- d5 2. The reaction was then quenched with a saturated aqueous NH 4 Cl solution. The residues were eluted through a silica gel column hexane: ethyl acetate to afford analytically pure 1a — d5 1. After stirring at this temperature for 30 min, HMPA 0. Subsequently, iodoethane 0. The residues were eluted through a silica gel column to afford 2a as an analytically pure white solid.

The NMR analysis agreed with the reported values [ 40 , 49 ]. The removal of H 2 with concomitant formation of 1 eq. Addition of 1 eq. Definitive assignment of diastereomers is hampered by closely overlapping peaks in the 1 H-NMR spectra and tentative assignments are made on the basis of previously reported NMR data of related allene complexes and 2-D NMR experiments.

After cooling to room temperature, the J-Young NMR tube was degassed using freeze-pump-thaw techniques. Subsequently, CO gas 1 atm.

Duplicate citations

The pincer iridium complex [ POCOP Ir] is capable of the facile isomerization of internal alkynes into disubstituted allenes. Deuterium labeling experiments provided support for a mechanism in which the metal-promoted activation of a C—H bond plays a key role and a primary kinetic isotope effect was measured. The rates of isomerization of a variety of alkyne substrates were measured over a broad temperature range, which allowed the thermodynamic parameters to be determined.

Olefin Metathesis

CHE used in this project. Neha Phadke and Michael Findlater conceived and designed the experiments; Neha Phadke performed the experiments and analyzed the data. The single crystal X-ray characterization data was collected and solved by Neha Phadke.

C-H bond activation reactions of ethers that generate iridium carbenes. - PubMed - NCBI

Neha Phadke and Michael Findlater wrote the paper. Sample Availability: Not available. Terms and Conditions Privacy Policy. We use cookies on our website to ensure you get the best experience.

US7902417B2 - Dual catalyst system for alkane metathesis - Google Patents

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    Chemistry of Materials , 31 7 , DOI: Marro, Eric M. Press, Maxime A. Siegler, Rebekka S. Journal of the American Chemical Society , 18 , Lara E. Spaniol, and Jun Okuda. Inorganic Chemistry , 56 24 , Organometallics , 35 15 , Journal of the American Chemical Society , 48 , Berlin, and Junha Jeon. ACS Catalysis , 5 6 , Journal of the American Chemical Society , 44 , Weller, Susan A.

    Nye, Kenrick M. Lewis, Johannes G. Delis, Julie L. Boyer, Aroop K. Roy, and Paul J. Journal of the American Chemical Society , 34 , Rory Waterman. Organometallics , 32 24 , Nickel-Catalyzed Cyclopolymerization of Hexyl- and Phenylsilanes. Organometallics , 32 4 , Sukesh Shekar and Seth N.

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