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  • 1
    Digitale Medien
    Digitale Medien
    Spectrophotometric studies on complex formation in dilute benzene solutions of [{Rh(diene)(μ–Cl)}2]–PR3–SnCl2 systems (1997)
    Springer
    Transition metal chemistry 22 (1997), S. 238-242 
    Details
    ISSN: 1572-901X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract There is no correlation between the stability of complexes formed in dilute solutions of [{Rh(diene)(μ–Cl)}2]–PR3–SnCl2 systems [with ligand combinations cod+PPh3, nbd+PPh3, cod+PPhMe2 and cod+ PCy3 (Cy=cyclohexyl)] and the possibility of isolating them as solids. In general, high dilution favours the formation of pentacoordinate complexes that decompose upon attempted crystallization. [RhCl(cod)(PPhMe2)2], [Rh(SnCl3)(cod)(PPh3)2], [Rh(SnCl3)(cod)(PCy3)2], [Rh(SnCl3)(cod)(PPhMe2)2] and [Rh(SnCl3)(nbd)(PPh3)2] have been identified in solution, but only the last two, previously known, have been isolated in the solid state. The steric properties of the coordinated phosphine seem to be the most important factor in determining the stabilities of [RhCl(diene)(PR3)2] complexes, whilst in the case of [Rh(SnCl3)(diene)(PR3)2] complexes the steric properties of the phosphine and the diene appear to have similar importance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018456206295
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Substitution of phosphine in the complex [RhCl(cyclooctadiene)(phosphine)] by 1-hexene (1989)
    Springer
    Transition metal chemistry 14 (1989), S. 105-109 
    Details
    ISSN: 1572-901X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The substitution of phosphine in the [RhCl(COD)(phosphine)] complex (1), where phosphine is PPh3 or 1/2 BPS-2 [bis(diphenylphosphinoethyl)tetramethyldisiloxane] and COD is cycloocta-1,5-diene, by 1-hexene is a two-step reversible reaction. All individual rate constants and equilibrium constants were determined spectrophotometrically and associative mechanism occurring via the formation of five-coordinated [RhCl(COD)(phosphine)(1-hexene)] (2) was inferred. The rate-determining step changes from the first- to the second-one as the concentration of 1-hexene increases. An excess of phosphine shifts the equilibrium towards complex (2).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01040601
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Stereoelectronic effects of substituents at silicon on the hydrosilylation of 1-hexene catalysed by [RhCl(cod)(1-hexene)] (1995)
    Springer
    Transition metal chemistry 20 (1995), S. 435-439 
    Details
    ISSN: 1572-901X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Trisubstituted silanes, HSiR3-n X n (R = Me or Et, X = Cl, OEt, or Ph; n = 0–3) oxidatively add to the complex [RhCl(cod)(1-hexene)] (cod = cycloocta-1,5-diene) to yield [RhCl(cod)(1-hexene)(H)(SiR3)] [(1)]. Subsequent steps of hydrosilylation follow, i.e. cis-insertion of the alkene (π-σ rearrangement) and then reductive elimination of the product, according to the general Chalk and Harrod scheme. A quantitative correlation between the second order rate constant, k 1, of the oxidative addition (followed spectrophotometrically) at 20°C in benzene solution and the structure of the trisubstituted silane represented by Stereoelectronic parameters χ,θ and E′' for the SiR3-n X n groups was established. The maximal hydrosilylation rate followed by g.l.c., is strongly retarded by highly electronegative substituents X on silicon and results from the elimination rate of the hydrosilylation product from (1) and the maximal concentration of (1) in solution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00141512
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Effect of oxidant on the reaction of [RhCl(cyclooctadiene)(phosphine)] with 1-hexene (1989)
    Springer
    Transition metal chemistry 14 (1989), S. 407-410 
    Details
    ISSN: 1572-901X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A promoting role of an oxidant, present in commercial 1-hexene, in the substitution of phosphine in the complex [RhCl(COD)(phosphine)] (1) where the phosphine is PPh3 or 1/2 BPS-2 [bis(diphenylphosphinoethyl)tetra-methyldisiloxane] and COD=cycloocta-1,5-diene, has been detected and explained. When [oxidant]〉[(1)] two reaction steps are distinguished: an oxidation of phosphine to phosphine oxide with generation of [RhCl(COD)], followed by its fast dimerization, and an oxidation of the dimer to RhIII species. When [oxidant]〈[(1)] the latter step is not observed and the reaction of [RhCl(COD)] with 1-hexene is favoured, particularly when an excess of phosphine (even at high oxidant concentration) is present. Most rate constants of the individual steps were evaluated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01092579
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of substituents at silicon on the oxidative addition of trisubstituted silanes to [RhCl(cod)PPh3] (1995)
    Springer
    Transition metal chemistry 20 (1995), S. 162-165 
    Details
    ISSN: 1572-901X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Trisubstituted silanes, HSiR3−n X n (R = Me, Et, Pr or Bu; X = Cl, OEt or Ph; and n = 0–3) readily undergo oxidative addition to complex [RhCl(cod)PPh3] (where cod = cycloocta-1,5-diene). The quantitative correlation between rate constants, k 1, of the reaction, followed spectrophotometrically at 20 °C in benzene solutions, and the structure of tri-substituted silanes represented by stereoelectronic parameters χ, θ and E″ of the substituents, was established: logk 1 = a + bχ + cθ + dE″. The reaction rate is accelerated by electron-withdrawing substituents at silicon and retarded by the bulk and pπ→dπ donation of nonalkyl substituents.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00167021
    Standort Signatur Erwartet Verfügbarkeit
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