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  • 1
    Electronic Resource
    Electronic Resource
    Preparation, Properties, and Reactions of Metal-Containing Hetercycles, XC. Reactivity of Differently Activated Alkynes toward Ruthenium and Osmium Complexes of the Type (η2-C2H4)M(CO)4Dedicated to Professor Reinhard Schmutzler on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1343-1347 
    Details
    ISSN: 0009-2940
    Keywords: Ruthenium compounds ; Osmium compounds ; Alkynes, activated ; Cyclotrimerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the substituents, the reaction of the activated alkynes ZC≡CZ (2a-g) [Z = CO2R: R = Me (a), Et (b); Z = R1: R1 = CF3 (c), CH2Cl (d), CH2Br (e); Z = CH2OC(O)R2: R2 = Me (f), CCl3 (g)] with the labile ruthenium complex (η2-C2H4)Ru(CO)4 (1) results in the formation of three different types of heterocycles. While the reactions of the dialkyl acet-ylenedicarboxylates 2a, b lead to the dimeric tricarbonylru-thenacyclopentadienes 3a, b, being catalytically active in the cyclotrimerization of alkynes like 2a, b, the application of the 1,4-halogeno-2-butynes 2c-e yields the bicyclic heterocycles 4c-e. The esters of 2-butyne-1,4-diol 2f, g are converted into the tetracarbonylruthenacyclopentadienes 5f, g. Investigation of the primary attack of the alkynes 2a-g at complex 1 leads to the conclusion, that an ionic mechanism is preferred in the ruthenium-catalyzed cyclotrimerization of electron-poor alkynes. If, instead of 1, (η2-C2H4)Os(CO)4 (6) is allowed to react with the acetylenes 2a, b the osmium complexes (η4-C6Z6)Os(CO)3 (7a, b) are isolated. In the presence of CO at 2 bar 7a, b release the benzene derivatives C6Z6 (8a, b) with the formation of Os3(CO)12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270803
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation, Properties, and Reactions of Metal-Containing Heterocycles, XCIPart XC: Ref.[1]. Insertion of Activated Alkynes and Sulfur into the P-P Bond of DiphosphamolybdacyclopropanesDedicated to Professor Herbert Schumann on the occasion of his 60th birthday (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 973-982 
    Details
    ISSN: 0009-2940
    Keywords: Molybdenum heterocycles ; P - P bonds ; Activated alkynes ; Sulfur ; Insertion reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The insertion of the alkynes ZC≡CZ (2a-i) [Z = Co2R: R = Me (a), Et (b), nPr (c), iPr (d), nBu (e), tBu (f), neo-Pent (g), cyc-Hex (h); Z = CF3 (i)] into the P1-P2 bond of the diphos-phamolybdacyclopropane Mes (1) (Mes = 2,4,6-trimethylphenyl) results in the formation of the diphosphamolybdacyclopentenes Mes (3a-i). According to an X-ray structural analysis, 3a crystallizes in the space group P21/c with the mesityl function at P2 and the cyclopentadienyl fragment at the metal atom on the opposite side of the planar five-membered ring. The same orientation is found in solution by NMR experiments (NOE; 2D 1H, 13C HETCOR). Kinetic investigations confirm that the rate constants decrease in the sequence R = Me 〉 Et 〉 nPr 〉 isoProp 〉 Cy 〉 nBu 〉 neo-Pent 〉 tBu. The second-order reaction and the strongly negative activation entropy which was determined in the case of the reaction 1 + 2e → 3e are consistent with a nucleophilic attack of P2 at one of the triply bonded carbon atoms of the alkyne. The reaction of 3a, h with sulfur affords the diastereomeric compounds Mes (4a, h). An X-ray structural analysis of the heterocycle 4h, which crystallizes in the space group P1, shows the presence of the enantiomeric pair SR/RS. The reaction of 1 with alkynes is hindered if this heterocycle is oxidized by sulfur to give Mes (5). Further reaction of 5 with sulfur leads to the ring-expanded heterocyclic intermediate (6) which crystallizes in the space group P1. The five-membered ring in 6 has an envelope conformation. Upon thermally induced cleavage of the P2S2Mes fragment from 6 the three-membered ring (7) is formed as the final product.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281003
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation, Properties, and Reactions of Metal-Containing Heterocycles, XCVPart XCIV: Ref.[1].. Transition-Metal-Mediated Cyclocotrimerization of Selenophosphinites with Activated AlkynesDedicated to Professor Rudolf Taube on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 945-951 
    Details
    ISSN: 0009-2940
    Keywords: Cyclocotrimerization ; Selenophosphinites ; Alkynes, activated ; Selenophenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selenophosphinito complexes (OC)4Mn(η2-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PR21) (2a, b) [R1 = cyc-Hex (a), tBu (b)] are formed by the reaction of BrMn(CO)5 with the phosphane selenides R21HPSe (1a, b) in the presence of the auxiliary base Et(iPr)2N. According to an X-ray structural analysis, 2a crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. The dimeric complex [(OC)4Mn(μ-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) is not obtained in a straightforward way. Compound 4c is only obtained via the intermediate Br(OC)4Mn-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}P(H)Me2 (3c) by HBr elimination with nBuLi. Complex 3c is formed by replacement of carbon monoxide in BrMn(CO)5 by Me2HPSe (1c). A dissociative equilibrium between [(OC)4 Mn(μ-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) and the monomeric species (OC)4Mn(\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}2-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2) was not observed. The cyclocotrimerization of the 〉P\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}Se function with the activated alkynes ZC≡CZ [Z = CO2R2; R2 = Me (d), Et (e), iPr (f), cyc-Hex (g)] was successful only in the case of the cyclohexyl derivative 2a to give the selenaphosphamanganabicycloheptadienes 5d - g. An X-ray structural analysis proved that 5d crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. Under CO pressure 5d was degraded to the selenophene 6.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290811
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