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Stoeckli-Evans, Helen

Nom
Stoeckli-Evans, Helen
Affiliation principale
Email
helen.stoeckli-evans@unine.ch
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https://libra.unine.ch/handle/123456789/470

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  • Publication
    Métadonnées seulement
    Synthesis and characterization of tetrahedral Ru3O clusters with intrinsic framework chirality: a chiral probe of the intact cluster catalysis concept. [Erratum to document cited in CA144:088385]
    (2006)
    Vieille-Petit, Ludovic
    ;
    Süss-Fink, Georg 
    ;
    Therrien, Bruno 
    ;
    Ward, Thomas R.
    ;
    Stoeckli-Evans, Helen 
    ;
    Labat, Gaeel
    ;
    Karmazin-Brelot, Lydia
    ;
    Neels, Antonia
    ;
    Buergi, Thomas
    ;
    Finke, Richard G.
    ;
    Hagen, Collin M.
    On page 6112, Figure 9 was missing and Figure 11 appeared twice. The correct Figure 9 is given. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Dinuclear ruthenium sawhorse-type complexes containing bridging ligands with ferrocenyl substituents in endo/endo, endo/exo and exo/exo orientations
    (2006)
    Auzias, Mathieu
    ;
    Therrien, Bruno 
    ;
    Labat, Gael
    ;
    Stoeckli-Evans, Helen 
    ;
    Süss-Fink, Georg 
    The dinuclear Ru complexes Ru2(CO)4(OOCC5H4FeC5H5)2L2 (L = py: 1, L = PPh3: 2) were synthesized from Ru3(CO)12, ferrocene carboxylic acid and pyridine or PPh3, resp. The single-crystal x-ray structure anal. reveals for 1 and 2 a Ru2(CO)4 sawhorse backbone with the two ferrocenyl substituents of the two carboxylato bridges being endo/exo with respect to each other in the solid state. With the new pyridine deriv. NC5H4OOCC5H4FeC5H5-4 (4-ferrocenoyloxypyridine) (3) as axial ligand, the complex Ru2(CO)4(OOCC5H4FeC5H5)2(NC5H4OOCC5H4FeC5H5-4)2 (4) was obtained, the single crystal x-ray structure anal. showing an exo/exo orientation of the two carboxylato bridges in the solid state. The endo/endo orientation is found in the solid-state structure of Ru2(CO)4(HNOCC5H4FeC5H5)2(PPh3)2 (5), the two OCNH bridges being transoid with respect to each other; this complex is accessible from Ru3(CO)12, ferrocenamide and PPh3. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Synthesis and Characterization of Tetrahedral Ru3O Clusters with Intrinsic Framework Chirality: A Chiral Probe of the Intact Cluster Catalysis Concept
    (2005)
    Vieille-Petit, Ludovic
    ;
    Süss-Fink, Georg 
    ;
    Therrien, Bruno 
    ;
    Ward, Thomas R.
    ;
    Stoeckli-Evans, Helen 
    ;
    Labat, Gaeel
    ;
    Karmazin-Brelot, Lydia
    ;
    Neels, Antonia
    ;
    Buergi, Thomas
    ;
    Finke, Richard G.
    ;
    Hagen, Collin M.
    Triruthenium mixed-ligand tetrahedral oxo-capped clusters with framework chirality were prepd. by redn. of areneruthenium triaqua dications followed by capping with areneruthenium dimer as racemic mixts.; diastereomeric mixts. were prepd. using chiral ligand; the prepd. complexes hydrogenate 2-acetamidoacrylate with no ee. Reaction of ArRuCl(?-Cl)2ClRuAr and Ar1RuCl(?-Cl)2ClRuAr1 with Ag2SO4 in aq. soln. gave mixt. of [ArRu(OH2)3]2+ and [Ar1Ru(OH2)3]2+, which upon NaBH4 redn. afforded mixed-ligand binuclear complex Ar1Ru(?-H)3RuAr (4, Ar = ?6-C6Me6, Ar1 = ?6-cymene). Reaction of 4 with Ar2RuCl(?-Cl)2ClRuAr2 and H2O gave the trinuclear cluster [(ArRu)(Ar1Ru)(Ar2Ru)(?3-O)(?-H)3]+ (rac-5, Ar2 = ?6-C6H6). Diastereomeric complexes [(ArRu)(Ar1Ru)(Ar*Ru)(?3-O)(?-H)3]+ [(S,R)-7, (R,R)-7; Ar* = (R)-1-phenylethanol] were prepd. by reaction of 4 with [Ar*RuCl(?-Cl)2ClRuAr*] (6). Analogous complex [(ArRu)(Ar1Ru)(Ar3Ru)(?3-O)(?-H)3]+ (8) was prepd. as a racemic mixt. from known (S,S)-Ar3RuCl(?-Cl)2ClRuAr3 [Ar3 = Et (R)-N-acetyl-?-aminobenzeneacetate]; the complex 8 was sepd. into diastereomers by chromatog., the racemization being caused by epimerization of the chiral ?-carbon. The enantiopure diastereomeric triruthenium clusters [(ArRu)(Ar1Ru)(Ar4Ru)(?3-O)(?-H)3]+ [(S,S)-17, (R,S)-17; Ar4 = (R)-N-acetyl-?-aminobenzeneethanol isobutyrate] were finally prepd. from (S,S)-Ar4RuCl(?-Cl)2ClRuAr4 and 4. The chiral Ru3O framework was evidenced by x-ray crystallog., by CD in the UV and IR regions, and by chiral shift reagents in the NMR spectra. To bring evidence for or against the hypothesis of catalytic hydrogenation by intact trinuclear arene ruthenium clusters contg. an oxo cap, catalytic hydrogenation of Me 2-acetamidoacrylate catalyzed by complexes 13 was performed; the complexes showed low catalytic activity and no asym. induction. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Framework fluxionality of organometallic oxides: Synthesis, crystal structure, EXAFS, and DFT studies on [{Ru(eta(6)-arene)}(4)Mo4O16] complexes
    (2004)
    Laurencin, Danielle
    ;
    Fidalgo, Eva Garcia
    ;
    Villanneau, Richard
    ;
    Villain, Françoise
    ;
    Herson, Patrick
    ;
    Pacifico, Jessica
    ;
    Stoeckli-Evans, Helen 
    ;
    Benard, Marc
    ;
    Rohmer, Marie-Madeleine
    ;
    Süss-Fink, Georg 
    ;
    Proust, Anna
    Reactions of the molybdates Na2MoO4.2H(2)O and (nBu(4)N)(2)[Mo2O7] with [{Ru(arene)Cl-2}(2)] (arene = C6H5CH3, 1,3,5-C6H3(CH3)(3), 1,2,4,5-C6H2(CH3)(4)) in water or organic solvents led to formation of the triple-cubane organometallic oxides [{Ru(eta(6)- arene)}(4)Mo4O16], whose crystal and molecular structures were determined. Refluxing triple cubane [{Ru(eta(6)-C6H5CH3)}(4)Mo4O16] in methanol caused partial isomerization to the windmill form. The two isomers of [{Ru(eta(6)-C6H5CH3)}(4)Mo4O16] were characterized by Raman and Mo K-edge X-ray absorption spectroscopy (XAS), both in the solid-state and in solution. This triple-cubane isomer was also used as a spectroscopic model to account for isomerization of the p-cymene windmill [{Ru(eta(6)-1,4-CH3C6H4CH(CH3)(2))}(4)Mo4O16] in solution. Using both Raman and XAS techniques, we were then able to determine the ratio between the windmill and triple-cubane isomers in dichloromethane and in chloroform. Density functional calculations on [{Ru(eta(6)-arene)}(4)Mo4O16] (arene=C6H6, C6H5CH3, 1,3,5-C6H3(CH3)(3), 1,4-CH3C6H4CH-(CH3)(2), C-6(CH3)(6)) suggest that the windmill form is intrinsically more stabel, provided the complexes are assumed to be isolated. Intramolecular electrostatic interactions and steric bulk induced by substituted arenes verse the energy difference between the isomers. The stability of the triple-cubane isomers should therefore be accounted for by effects of the surroundings that induce a shift in the energy balance between both forms.
  • Publication
    Métadonnées seulement
    Di-mu-acetato-kappa O-4 : O '-tetracarbonylbis(pyridyl-2-yl-kappa N-amine)diruthenium(I)(Ru-Ru)
    (2004)
    Dorta, Reto
    ;
    Süss-Fink, Georg 
    ;
    Stoeckli-Evans, Helen 
    The structure of the title compound, [Ru-2(C2H3O2)(2)(C5H6N2)(2)(CO)(4)], consists of a 'sawhorse' diruthenium complex with two acetate bridges and two 2-aminopyridine ligands in the axial positions, coordinating via the pyridine N atoms. A double-stranded hydrogen-bonded chain is formed via intra- and intermolecular hydrogen bonds involving the amine groups, one O atom of both acetate groups and two carbonyl O atoms.
  • Publication
    Métadonnées seulement
    Iron, cobalt, nickel and ruthenium complexes of 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine, a pybox analogue
    (2003)
    Cabort, Amel 
    ;
    Michel, Armelle
    ;
    Therrien, Bruno 
    ;
    Stoeckli-Evans, Helen 
    ;
    Bernauer, Klaus
    ;
    Süss-Fink, Georg 
    ;
    Williams, Alan F.
    ;
    Stupka, Gilles
    The coordination of 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine (L) to Ni, Ru, Fe, and Co was studied. The reaction with Ni salts gives the Ni(II) complex [Ni(L)2]2+ (1). The reaction of RuCl3 gives only the Ru(II) complex [Ru(L)2]2+ (2). In the case of Fe, both [Fe(L)2]2+ (3) and [Fe(L)2]3+ (4) were synthesized and characterized. In the case of Co, the Co(III) complex [Co(L)2]3+ (5) was obtained, even if a Co(II) salt was used. However, [Co(L)2]2+ (6) can be obtained under N. Mol. structures of 1-5 complexes were detd. by x-ray anal. of the corresponding perchlorate salts; the structure of 3 was solved for both the perchlorate and the tetrachloroferrate(III) salts. All complexes show an octahedral coordination geometry with meridional arrangement of the two tridentate ligands. The electrochem. behavior of 2, 3 and 6 was studied by cyclic voltammetry. Quasi reversible electron transfer is obsd. for the redox pairs FeIII/FeII and CoII/CoI. The reaction shows somewhat weaker reversibility for CoIII/CoII, whereas the reaction of RuIII/RuII is not reversible. The measurements suggest 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine (L) to have a higher stabilization of low-valent oxidn. states of Fe and Co than terpyridine. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Ru-4(mu-CO)(CO)(9)(eta(4)-mu(4)-C6H4)(eta(2)-mu(1), mu(4)-PPhCH2CH2PPh2): an unusual pyrolysis product of Ru-3(CO)(10)(dppe) containing a benzyne ligand
    (2002)
    Diz, Enrique Lozano
    ;
    Neels, Antonia
    ;
    Stoeckli-Evans, Helen 
    ;
    Süss-Fink, Georg 
    The thermal decomposition of Ru-3(CO)(10)(dppe) in refluxing benzene gives, in contrast to the pyrolysis of the dppm analogue, the tetranuclear cluster Ru-4(mu-CO)(CO)(9)(eta(4)-mu(4)-C6H4) (eta(2)-mu(1), mu(4)-PCH2CH2PPh2) (1) along with Ru-3 (CO)(9)(eta(2)-mu(1), mu(2)-C6H5)(eta(3)-mu(1), mu(2)-PPhCH2CH2PPb2) (2). The single-crystal structure analysis of 1 reveals a square-planar tetraruthenium skeleton containing a eta(4)-mu(4)-benzyne ligand as well as a eta(2)-mu(1), mu(4)-phosphinidene-phosphine ligand. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Publication
    Métadonnées seulement
    A cluster containing a pyrazole ligand: [Ru3(?-H)(?-N2C3H3)(CO)10]
    (2002)
    Diz, Enrique Lozano
    ;
    Neels, Antonia
    ;
    Therrien, Bruno 
    ;
    Stoeckli-Evans, Helen 
    ;
    Süss-Fink, Georg 
    The title cluster decacarbonyl-1?4C,2?3C,3?3C-?-hydrido-2:3?2H:H-?-pyrazolyl-2:3?2N1:N2-triangulo-triruthenium, [Ru3(?-H)(?-C3H3N2)(CO)10], which contains a pyrazole ligand, was synthesized and characterized, both spectroscopically and crystallog., as a cyclohexane solvate. Crystals are monoclinic, space group I2/a, with a 14.2248(11), b 9.1670(5), c 59.834(5) Å, ? 90.380(9)°; Z = 8 (2 mols./Z), dc = 2.290; R = 0.041, Rw(F2) = 0.107 for 4743 reflections. The mol. structure is very similar to that of the known dimethylpyrazole deriv. [Ru3(?-H){?-N2C3HMe2-3,5}(CO)10]. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Ligand dehydrogenation in ruthenium trinitrogen complexes: synthesis, structure and chirality of the cations [Ru(LH4)(L)]2+ [LH4 = 2,6-bis(pyrrolidin-2-yl)pyridine]
    (2002)
    Cabort, Amel 
    ;
    Therrien, Bruno 
    ;
    Stoeckli-Evans, Helen 
    ;
    Bernauer, Klaus
    ;
    Süss-Fink, Georg 
    Reaction of 2,6-bis(pyrrolidin-2-yl)pyridine (LH4) with RuCl3·3H2O in refluxing MeOH/H2O mixts. gives the octahedral complexes [Ru(LH4)(L)]2+, in which one of the two trihapto ligands was dehydrogenated as 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine (L), even if LH4 was present in excess. With the three stereoisomers of LH4, [Ru(R,S-LH4)(L)]2+ (meso), [Ru(R,R-LH4)(L)]2+ and [Ru(S,S-LH4)(L)]2+ were isolated as the perchlorate salts and characterized by x-ray structure anal. and by CD spectra. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    N,N'-Dicyclohexyl-N-(2-pyrazinoyl)urea
    (2002)
    Cherioux, Frederic
    ;
    Therrien, Bruno 
    ;
    Stoeckli-Evans, Helen 
    ;
    Süss-Fink, Georg 
    The title compd. is obtainable from 1,3-dicyclohexylcarbodiimide and pyrazine-2-carboxylic acid in DMF in the presence of catalytic amts. of [H3Ru4(C6H6)4OH]Cl2. Crystals of the compd. are orthorhombic, space group P212121, with a 9.4745(8), b 11.9101(7), c 15.8212(10) Å; Z = 4, dc = 1.229; R = 0.028, Rw(F2) = 0.058 for 3477 reflections. The intermol. N-H...O=C H bond is responsible for the formation of infinite chains stretching along the a axis of the crystal. [on SciFinder(R)]