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Stoeckli-Evans, Helen
Nom
Stoeckli-Evans, Helen
Affiliation principale
Fonction
Professeur.e émérite
Email
helen.stoeckli-evans@unine.ch
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Résultat de la recherche
Voici les éléments 1 - 10 sur 17
- PublicationAccès librePreparation of donor–acceptor substituted fluorostilbenes and crystal chemistry of fluorinated (E)-4-(4-halogeno-styryl)-benzonitriles(2009)
; Hulliger, JürgThe syntheses and crystal structures of a series of fluoro-substituted halogeno (Cl, Br, I)-cyano-stilbenes containing donor and acceptor groups (D-π-A) are reported. These molecules show a tendency to form antiparallel chain-like structures and herringbone packing, crystallising predominantly in a centric space group. However, second harmonic generation measurements bear evidence for orientational disorder leading to partial polar order below the ordinary X-ray structure determination limit. Some co-crystals are isostructural with their components. The non-fluoro as well as the halogeno-fluoro substituted components of co-crystals seem to impose their crystal structure on the complementary fluoro- or cyano–fluoro substituted components. Co-crystallization enhanced the deviation from centrosymmetry. - PublicationAccès libreAn efficient one-pot synthesis of strongly fluorescent (hetero)arenes polysubstituted with amino and cyano groups(2008)
; - PublicationAccès libreThree-dimensional bimetallic octacyanidometalates [MIV{(μ-CN)4MnII (H2O)2}2•4H2O]n (M = Nb, Mo, W): Synthesis, single-crystal X-ray diffraction and magnetism(2008)
; - PublicationAccès libreThe High Stereoselectivity of the Tandem Sequence Diels-Alder Reaction/Ireland-Claisen Rearrangement Starting from Substituted O-(E)-Buta-1,3-dienyl Ketene Acetals and Cyclic Dienophiles(2007)
; A new tandem reaction leads to bicyclic cyclohexene derivatives with complete control of the relative configuration of the four chiral centers formed. The high diastereoselectivity is the consequence of an endo-selective Diels-Alder reaction followed by an Ireland-Claisen rearrangement that proceeds via a boat-like transition state. - PublicationAccès libreSynthesis, crystal structures and spectra of Hg(II)-1,2-bis(diphenylphosphino)ethane monoxide complexes: Monomer and polymer formation(2007)
; Panchanatheswaran, KrishnaswamyThe reaction of mercury(II) halides with 1,2-bis(diphenylphosphino)ethane monoxide (dppeO) in 1:1 molar ratio yielded P,O-coordinated polymers having the empirical formula [HgX2 (dppeO)]n [X = Cl (1), Br (2), I (3)]. In contrast, the reaction between the same reactants in a 1:2 molar ratio yielded the P, P-coordinated monomeric complexes, HgX2 (dppeO)2[X = Cl (4), Br (5), I (6)]. The structures of 2, 3, 4 and 5 have been characterized crystallographically. The results indicate that the geometry around the mercury atom in each of these molecules is tetrahedral with considerable distortion. The 31P NMR spectra of the 1:1 complexes indicate the dissociation of the Hg–O bond in solution. - PublicationAccès libreSynthesis and structural analysis of palladium biscarbene complexes derived from bisimidazolium ligand precursors(2006)
; Albrecht, MartinThe palladation of potentially chelating bisimidazolium ligand precursors with palladium acetate gives bridging bimetallic, chelating monometallic, and homoleptic tetracarbene complexes. The coordination mode of the biscarbene ligand has been identified by spectroscopic analysis and crystallographic characterization of representative complexes, including the first example of a biscarbene A-frame structure. Substantial concentrations of free acetate favor the formation of tetracarbene over biscarbene palladium complexes, while in the absence of a base, the concentration of reactants influences the selectivity for bridging bimetallic versus chelating monometallic species. Preliminary kinetic and mechanistic studies indicate that chelating biscarbene palladium acetate complexes are intermediates in the formation of the homoleptic tetracarbene complexes. Probably due to the high trans effect of the biscarbene ligand, such complexes are more efficient palladating agents for bisimidazolium salts than palladium acetate. - PublicationAccès libreOrganosulfur donor with hydroxy groups and its conducting salt: crystal structures and physical properties(2004)
; - PublicationAccès libreThe Synthesis of a Pyrazol Analogon of Porphobilinogen with the Help of the Mukaiyama Aldol Reaction(2003)
; The synthesis of a pyrazol analogon of porphobilinogen is described. The Mukaiyama crossed aldol reaction is the key step of our approach. The retrosynthetic analysis follows the mechanism for the biosynthesis of porphobilinogen initially proposed by Shemin. - PublicationAccès libreRhodium-Catalysed Carbonylation of Methanol Using a New Multifunctional Ligand - Isolation and Structural Characterisation of the Macrocycle [Rh2I6(CO)2(C6H4N3CH2CO2C4H2SCO2CH2C6H4N3)]2(2001)
; The new multifunctional ligand thiophene-2,5-bis(carboxylatomethylenebenzotriazole) (1) reacts with [RhCl(CO)2]2 to give the rhodium complex [RhCl(CO)(1)]2 (2), which was found to catalyse efficiently the iodide-mediated carbonylation of methanol. The macrocyclic carbonyliodorhodium complex [Rh2I6(CO)2(1)]2 (3) was isolated from the catalytic mixture and structurally characterised. - PublicationAccès libreNucleophilic addition reactions on the electron-deficient cluster dication [H4Ru4(C6H6)4]2+ : synthesis and structural characterisation of the water-soluble cluster cations [H3Ru4(C6H6)4 (CO)]+ and [H3Ru4(C6H6)4 (OH)]2(2001)
; The electron-deficient (58e) cluster cation [H4Ru4(C6H6)4]2+1 was found to react in aqueous solution with simple nucleophiles to give electron-precise (60e) clusters. With carbon monoxide, the cluster cation [H3Ru4(C6H6)4(CO)]+3 is formed. The reaction with water needs NaN3 as catalyst and yields the cluster dication [H3Ru4(C6H6)4 (OH)]2+4a; the reaction with alcohols leads to the analogous clusters [H3Ru4(C6H6)4 (OR)]2+ (R = Me: 4b, R = Et: 4c, R = PhCH2: 4d, R = Ph: 4e, R = 4-EtC6H4: 4f). The single-crystal X-ray structure analyses of the chloride salts of 3 and 4a reveal a tetrahedral Ru4 metal core. Each ruthenium atom is coordinated by a η6-benzene ligand, while the carbonyl or hydroxo ligands are found as µ3 capping ligands over a triangular face of the Ru4 tetrahedron.