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Stoeckli-Evans, Helen

Nom
Stoeckli-Evans, Helen
Affiliation principale
Fonction
Professeur.e émérite
Email
helen.stoeckli-evans@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/470
_
0000-0002-9960-3869

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  • Publication
    Métadonnées seulement
    The mixed-metal carbonyl cluster anion [Os3Ir(CO)(13)](-): Synthesis, structure, reactivity and catalytic activity in the carbonylation of methanol
    (1999)
    Süss-Fink, Georg 
    ;
    Haak, Susanne
    ;
    Ferrand, Vincent
    ;
    Stoeckli-Evans, Helen 
    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
    Site-selective carbonyl substitution in the mixed-metal cluster anion [H2Ru3Ir(CO)(12)](-): synthesis and characterization of phosphine, phosphite, arsine and stibine derivatives
    (1999)
    Süss-Fink, Georg 
    ;
    Haak, Susanne
    ;
    Ferrand, Vincent
    ;
    Neels, Antonia
    ;
    Stoeckli-Evans, Helen 
    The reaction of the mixed-metal carbonyl cluster anion [H2Ru3Ir(CO)(12)](-) with PPh3, PMe3, P(OPh)(3), AsPh3 or SbPh3 leads to the mono-substituted derivatives [H2Ru3Ir(CO)(11)L](-) (L = PPh3 1, L = PMe3 2, L = P(OPh)(3) 3, L = AsPh3 4, L = SbPh3 5). Protonation of the anions 1-5 gives the neutral trihydrido derivatives H3Ru3Ir(CO)(11)L (L = PPh3 6, L = PMe3 7, L = P(OPh)(3) 8, L = AsPh3 9, L = SbPh3 10). All new tetranuclear clusters invariably show a tetrahedral arrangement of the Ru3Ir skeleton, as predicted for 60 e systems. The ligand L is coordinated to one of the ruthenium atoms, except in the case of L = PMe3 where two substitution isomers are observed. While the anionic isomers [H2Ru3Ir(CO)(11)(PMe3)](-) (2) could not be separated, the corresponding neutral isomers H3Ru3Ir(CO)(11)(PMe3) (7) could be resolved by thin-layer chromatography. In isomer 7a, the phosphine ligand is coordinated to one of the ruthenium atoms, whereas in isomer 7b the PMe3 ligand is bonded to the iridium atom. The molecular structures of 1, 7b, 8 and 9 were confirmed by a single-crystal X-ray structure analysis. (C) 1999 Elsevier Science S.A. All rights reserved.
  • Publication
    Accès libre
    The mixed-metal carbonyl cluster anion [Ru3Ir(CO)13]– : synthesis, molecular structure, fluxionality, reactivity
    (1997)
    Süss-Fink, Georg 
    ;
    Haak, Susanne
    ;
    Ferrand, Vincent
    ;
    Stoeckli-Evans, Helen 
    The new cluster anion [Ru3Ir(CO)13]–1 was synthesized in high yield from [Ru3(CO)12] and [Ir(CO)4]–. The single-crystal X-ray structure analysis of the bis(triphenylphosphoranylidene)ammonium salt revealed the presence of two isomers, [Ru3Ir(CO)11(µ-CO)2]–1a and Ru3Ir(CO)9(µ-CO)4]–1b in the same crystal. Both 1a and 1b present a tetrahedral Ru3Ir framework, differing only by the number of bridging carbonyl ligands. Variable-temperature 13C NMR spectroscopic studies of 1 revealed the fluxionality of the carbonyl ligands and the interconversion of both isomers in solution. Protonation of 1 gave the neutral cluster [HRu3Ir(CO)13] 2, whereas reaction of 1 with molecular hydrogen yielded the anion [H2Ru3Ir(CO)12]–3. Either hydrogenation of 2 or protonation of 3 gave [H3Ru3Ir(CO)12] 4. The tetrahedral structure of the hydrido derivatives was confirmed by a single-crystal X-ray structure analysis of the bis(triphenylphosphoranylidene)ammonium salt of 3.