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Stoeckli-Evans, Helen
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Stoeckli-Evans, Helen
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helen.stoeckli-evans@unine.ch
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- PublicationMétadonnées seulementFramework fluxionality of organometallic oxides: Synthesis, crystal structure, EXAFS, and DFT studies on [{Ru(eta(6)-arene)}(4)Mo4O16] complexes(2004)
; ; Proust, AnnaReactions 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. - PublicationMétadonnées seulementThe anion [(As5Mo4O20)-Mo-III-O-VI(OCH3)](2-): a new heteropolyoxometalate containing an unusual As5O4 chain(2002)
; The heteropolyoxometalate [(HAsAsMoMo8O34)-As-III-Mo-V-Mo-V-O-VI](6-) reacts in aqueous solution with an excess of sodium metaarsenite to give a new arsenomolybdate [(As5Mo4O20)-Mo-III-O-VI(OCH3)](2-) which crystallize as the tetrabutylammonium salt. The single-crystal X-ray structure analysis reveals a heteropolyoxometalate anion containing an unusual chain of five arsenic atoms linked to each other by bridging oxygen atoms. (C) 2002 Elsevier Science B.V. All rights reserved. - PublicationMétadonnées seulementNew iso and heteropolyoxomolybdates: synthesis and molecular structure of the anions [(Mo8O26)-O-VI(OH)](5-), [(HAsAsMoMo8O34)-As-III-Mo-V-Mo-V-O-VI](6-) and [(HAsAsMoMo8O34)-As-III-Mo-V-Mo-V-O-VI{Co(C5H5N)(2)(H2O)(3)}](4-)(2002)
; The hydrothermal reaction of Na2MoO4 with pyridine in water at pH 5 and 130 degreesC gives the octamolybdate anion [Mo-8(VI) O-26(OH)](5-) (1) which crystallises as the pyridinium salt; its molecular structure derives from that of the parent alpha-octamolybdate anion [Mo-8(VI) O-26](4-) by opening two molybdenum-oxygen bond and adding a hydroxo bridge. The same reaction in the presence of NaAsO2 yields the mixed-valence arsenatomolybdate [Has(III)As(V)Mo(V)Mo(8)(VI)O(34)](6-) (2) which is also isolated as the pyridinium salt. Anion 2 has a lacunary structure like an open basket, which derives from the famous alpha-Keggin structure by removing three edge-sharing MoO6 octahedra and by capping a trioxygen face of three remaning MoO6 octahedra with an AsH group. Reaction of 2 with Co2+ leads to the anion [(HAsAsMoMo8VI)-As-III-Mo-V-Mo-V O-34 {Co(C5H5N)(2)(H2O)(3)}](4-) (3) which crystallises as a double pyridinium salt together with anion 2. The structure of 3 derives from that of 2 by attaching a Co(C5H5N)(2)(H2O)(3) fragment to a terminal oxo ligand. Reaction of 2 with hydrogen peroxide produces the fully oxydised alpha-Keggin anion [(AsMo12O40)-Mo-V-O-VI](3-) (4) which was found to crystallise as the tetrabutylammonium salt surprisingly with three independent molecules in the unit cell, two of them showing a remarkable disorder. (C) 2002 Elsevier Science Ltd. All rights reserved. - PublicationMétadonnées seulementCationic 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)
; 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. - PublicationMétadonnées seulementReactivity 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)
; - PublicationMétadonnées seulementDi-mu-bromo-bis[bromo(eta(6)-para-cymene)-ruthenium(II)] benzene solvate and di-mu-iodo-bis[(eta(6)-para-cymene)iodoruthenium(II)] toluene solvate(1999)
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