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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
    Cationic dinuclear arene ruthenium complexes with one hydroxo and two chloro bridges: synthesis and molecular structure of [(p-Me-C6H4 Pr-i)(2)Ru-2(mu-Cl)(2)(mu-OH)][ReO4]
    (2001)
    Fidalgo, Eva Garcia
    ;
    Plasseraud, Laurent
    ;
    Stoeckli-Evans, Helen 
    ;
    Süss-Fink, Georg 
    The dinuclear complexes (arene)(2)Ru2Cl4 (arene = benzene, p-cymene, durene, hexamethylbenzene) react in aqueous solution to give, in addition to the known cationic trichloro complexes [(arene)(2)Ru-2(mu -Cl)(3)](+), the new dichloro hydroxo cations [(arene)(2)Ru-2(mu -Cl)(2)(mu -OH)](+) which can be isolated as the perrhenate salts. (C) 2001 Published by Elsevier Science B.V.
  • Publication
    Métadonnées seulement
    Reactivity of dinuclear arene ruthenium complexes: reactions of the hydrido complex [(p-Me-C6H4-Pr-i)(2)Ru2Cl2(mu-Cl)(mu-H)] with NaX and HX (X = F, Cl, Br, I)
    (2000)
    Süss-Fink, Georg 
    ;
    Fidalgo, Eva Garcia
    ;
    Neels, Antonia
    ;
    Stoeckli-Evans, Helen 
    The dinuclear hydride complex [(p-Me-C6H4-Pr')(2)Ru2Cl2(mu-Cl)(mu-H)] (1) reacts with the sodium halides NaX in methanol to give the halogen analogues [(p-Me-C6H4-Pr')(2)Ru2X2(mu-X)(mu-H)] (2: X = F, 3: X = Br, 4: X = I). With HX, complex 1 reacts to give the tetrahalo complexes [(p-Me-C6H4-Pr')(2)Ru2X2(mu-X)(2)] (5: X = Cl, 6: X = Br, 7: X = I); in the case of X = I, a large excess of HI leads to the formation of the cationic complex [(p-Me-C6H4-Pr')(2)Ru-2(mu-I)(3)](+) (8). The X-ray structure analysis of 1 shows a dinuclear Ru-2 backbone with two terminal chloro ligands being irans with respect to each other as the two p-cymene ligands, the two bridging ligands lie in a plane perpendicular to the plane defined by the terminal chloro ligands and the ruthenium atoms. (C) 2000 Elsevier Science S.A. All rights reserved.
  • Publication
    Métadonnées seulement
    The cluster dication [H6Ru4(C6H6)(4)](2+) revisited: the first cluster complex containing an intact dihydrogen ligand?
    (2000)
    Süss-Fink, Georg 
    ;
    Plasseraud, Laurent
    ;
    Maisse-Francois, Aline
    ;
    Stoeckli-Evans, Helen 
    ;
    Berke, Heinz
    ;
    Fox, Thomas
    ;
    Gautier, Régis
    ;
    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.