• Pd2Au36(SR)24 cluster: structure studies
    B. Zhang, S. Kaziz, H. Li, D. Wodka, S. Malola, O.V. Safonova, M. Nachtegaal, C. Mazet, I. Dolamic, J. Llorca, E. Kalenius, L.M. Lawson Daku, H. Häkkinen, T. Buergi and N. Barrabes
    Nanoscale, 7 (40) (2015), p17012-17019
    DOI:10.1039/C5NR04324G | unige:75923 | Abstract | Article HTML | Article PDF | Supporting Info
The location of the Pd atoms in Pd2Au36(SC2H4Ph)24, is studied both experimentally and theoretically. X-ray photoelectron spectroscopy (XPS) indicates oxidized Pd atoms. Palladium K-edge extended X-ray absorption fine-structure (EXAFS) data clearly show Pd-S bonds, which is supported by far infrared spectroscopy. By comparing theoretical EXAFS spectra in R space and circular dichroism spectra of the staple, surface and core doped structures with experimental spectra.
  • Modulation of Active Sites in Supported Au38(SC2H4Ph)24 Cluster Catalysts: Effect of Atmosphere and Support Material
    B. Zhang, S. Kaziz, H. Li, M. Gonzalez Hevia, D. Wodka, C. Mazet, T. Bürgi and N. Barrabés Rabanal
    The Journal of Physical Chemistry C, 119 (20) (2015), p11193-11199
    DOI:10.1021/jp512022v | unige:72892 | Abstract | Article HTML | Article PDF
We investigate the distinctly different interaction of thiolate-protected cluster Au38(SC2H4Ph)24with two diverse support materials Al2O3 and CeO2. The catalytic surfaces have been heated in different atmospheres, and the removal of the thiolate ligands has been studied. Thermogravimetry (TG), temperature-programmed process coupled with mass spectrometer (TPRDO-MS), and X-ray absorption spectroscopy (XAFS) studies were performed to understand the desorption of thiol ligands depending on conditions and support material. Depending on the atmosphere and the support material the fate of the thiol ligands is different upon heating, leading to metallic Au in the case of Al2O3 and to cationic Au with CeO2. The thiolate removal seems to be a two-step procedure. The catalytic activity of these Au38-supported clusters was studied for the aerobic oxidation of cyclohexane. Conversion was higher for the gold clusters supported on CeO2. Surprisingly, a significant amount of cyclohexanethiol was found, revealing the active participation of the thiolate ligand in catalytic reactions. The observation also indicates that breaking and formation of C–S bonds can be catalyzed by the gold clusters.
  • Access to Enantioenriched 2,3- and 2,5-Dihydrofurans with a Fully Substituted C2 Stereocenter by Pd-Catalyzed Asymmetric Intermolecular Heck ReactionOpen access paper
    G.M. Borrajo-Calleja, V. Bizet, T. Buergi and C. Mazet
    Chemical Science, 6 (8) (2015), p4807-4811
    DOI:10.1039/C5SC01460C | unige:74172 | Abstract | Article HTML | Article PDF | Supporting Info
A palladium catalyzed intermolecular asymmetric Heck reaction with cyclic trisubstituted olefins is reported. The use of two different chiral ligands provides access to valuable 2,3- and 2,5-dihydrofurans with a fully substituted C2 stereocenter with high levels of regio- and enantiocontrol.

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