Voici les éléments 1 - 6 sur 6
  • Publication
    Métadonnées seulement
    The cluster dication [(eta(6)-C6H6)(2)(eta(6)-C6Me6)(4)Ru-8(mu(2)-H)(2)(mu(3)-O)(2)(mu(2)-Cl) (2)](2+): a chloro-bridged framework containing two metal tetrahedra
    The title complex was obtained by reacting [(eta(6)-C6H6)(eta(6)-C6Me6)(2)Ru-3(mu(2)-H)(3)(mu(3)-O)(+) with RuCl3 . nH(2)O in aqueous solution. it crystallises as the tetrafluoroborate salt. The cationic cluster is formed of two tetrahedral Ru-4 substructures which are held together by two chloro bridges. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Publication
    Métadonnées seulement
    The cluster dication [H6Ru4(C6H6)(4)](2+) revisited: the first cluster complex containing an intact dihydrogen ligand?
    (2000) ;
    Plasseraud, Laurent
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    Maisse-Francois, Aline
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    Berke, Heinz
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    Fox, Thomas
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    Gautier, Régis
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    Saillard, Jean-Yves
    A low-temperature H-1-NMR study suggests the tetranuclear cluster dication [H6Ru4(C6H6)(4)](2+) (1) to contain an H-2 ligand that undergoes, upon warming of the solution, an intramolecular exchange with the four hydride ligands at the Ru-4 framework. Whereas two of the three NMR signals at - 120 degrees C in the hydride region show T-1 values in the range 200-300 ms, the least deshielded resonance at delta = - 17.33 ppm exhibits a T-1 value of only 34 ms, characteristic of an H-2 ligand. a re-examination of the single-crystal X-ray structure analysis of the chloride salt of 1 supports this interpretation by a short distance of 1.14(0.15) Angstrom between two hydrogen atoms coordinated as a PI-PI ligand in a side-on fashion to one of the triangular faces of the Ru-4 tetrahedron. The distance between one of the two hydrogen atoms of the H-2 ligand and one of the four hydride ligands is also very short [1.33(0.15) Angstrom], suggesting an additional H-2... H interaction. The presence of this H-3, unit over one of the three Ru-3 faces in 1 may explain the deformation of the Ru-4 skeleton from the expected tetrahedral symmetry. Density functional theory (DFT) calculations on 1 indicate a very soft potential energy surface associated with the respective displacement of the three interacting cofacial hydrogen atoms. In accordance with these results, the cluster dication 1 tends to loose molecular hydrogen to form the cluster dication [H4Ru4(C6H6)(4)](2+) (2). The equilibrium between 1 and 2 can be used for catalytic hydrogenation reactions. (C) 2000 Elsevier Science S.A. All rights reserved.
  • Publication
    Métadonnées seulement
    The mixed-metal carbonyl cluster anion [Os3Ir(CO)(13)](-): Synthesis, structure, reactivity and catalytic activity in the carbonylation of methanol
    (1999) ;
    Haak, Susanne
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    Ferrand, Vincent
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    The cluster anion [Os3Ir(CO)(13)](-) (1) was prepared in 50% yield by reaction of Os-3(CO)(12) with [Ir(CO)(4)](-). The single-crystal X-ray structure analysis of the bis(triphenylphosphoranylidene)ammonium salt shows 1 to consist of a tetrahedral metal core with one of the 13 carbonyl ligands being bridging. Protonation of 1 led to the neutral cluster HOs3Ir(CO)(13) (2), whereas the hydrogenation gave the cluster anion [H2Os3Ir(CO)(12)](-) (3). The catalytic activity of 1 for the carbonylation of methanol was studied. Using CH3I as co-catalyst, catalytic turnover numbers up to 1800 were obtained (140 degrees C, 30 bar) within 14 h. (C) 1999 Elsevier Science B.V. All rights reserved.
  • Publication
    Métadonnées seulement
    Electron-deficient triruthenium and triosmium clusters from the reaction of the cluster anions [HM3(CO)(11)](-) (M = Ru, Os) with tricyclohexylphosphine in methanol
    (1999) ;
    Godefroy, Isabelle
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    Ferrand, Vincent
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    Neels, Antonia
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    Kahlal, Samia
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    Saillard, Jean-Yves
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    Garland, Maria Teresa
    The reaction of Na[HRu3(CO)(11)] with an excess of tricyclohexylphosphine in methanol gives the neutral complex H2Ru3(CO)(6)(PCy3)(3) which is the first 44 e(-) triruthenium cluster reported. This highly electron-deficient species reacts with carbon monoxide to give the saturated 48 e(-) cluster Ru-3(CO)(9)(PCy3)(3). The electronic structure of the novel 44 e- cluster was established by EHT and DFT molecular orbital calculations of isoelectronic model compounds. The analogous reaction of [N(PPh3)(2)][HOs3(CO)(11)] with PCy3 in methanol affords the 46 e(-) cluster H2Os3(CO)(7)(PCy3)(3), the first trisubstituted derivative of H2Os3(CO)(10). In all cases methanol acts as source of protons for the formation of the hydride clusters. (C) 1999 Elsevier Science S.A. All rights reserved.
  • Publication
    Métadonnées seulement
    Electron-deficient triruthenium clusters: synthesis and molecular structure of the anion [HRu3(CO)(7)(PCy3)(2)](-), a second example of an Ru-3 cluster presenting an electron count of 44 electrons
    (1999)
    Godefroy, Isabelle
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    The reaction of [HRu3(CO)(11)](-) (1) with an excess of PCy3 in refluxing THF gives the electron-deficient anion [HRu3(CO)(7)(PCy3)(2)](-) (2) which has the rare electron count of 44e. As evidenced by the H-1 and P-31 NMR spectra, 2 exists in solution in the form of two isomers 2a and 2b, one of which crystallises from acetone as the tetraethylammonium salt. The single-crystal X-ray analysis shows a closed Ru, framework with the hydride ligand bridging the metal-metal bond between a phosphine-substituted and a phosphine-free ruthenium atom (isomer 2b). (C) 1999 Elsevier Science S.A. All rights reserved.
  • Publication
    Métadonnées seulement
    Fixation of triruthenium clusters on melamine: synthesis and structure of [Ru-3(mu(2)-H)(CO)(9){mu(3),eta(2)-NHC3N3(NH2)(2)}], cis-[{Ru-3(mu(2)-H)(CO)(9)}(2){mu(3),eta(2):mu(3),eta(2)-NHC3N3(NH2)}] and trans-[{Ru-3(mu(2)-H)(CO)(9)}(2){mu(3),eta(2):mu(3),eta(2)-NHC3N3(NH2)}]
    (1998)
    Dorta, Reto
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    Bodensieck, Ulf
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    Melamine, C3N3(NH2)(3), was found to react with [Ru-3(CO)(12)] to give, with N-H activation, the monometallated derivative [Ru-3(mu(2)-H)(CO)(9){mu(3),eta(2)-NHC3N3(NH2)(2)}] (1) and the two isomeric bimetallated derivatives cis-[{Ru-3(mu-H)(CO)(9)}(2){mu(3),eta(2) : mu(3),eta(2) - NHC3N3(NH2)}] (cis-2) and trans-[{Ru-3(mu-H)(CO)(9)}(2){mu(3),eta(2) : mu(3),eta(2)-NHC3N3(NH2)}] (trans-2). The molecular structures of 1, cis-2 and trans-2 have been determined by single-crystal X-ray crystallography. (C) 1998 Elsevier Science S.A.