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  • 1970-1974  (5)
  • 1974  (5)
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  • 1970-1974  (5)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @British journal for the history of science 7 (1974), S. 287-287 
    ISSN: 0007-0874
    Source: Cambridge Journals Digital Archives
    Topics: History , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @British journal for the history of science 7 (1974), S. 95-95 
    ISSN: 0007-0874
    Source: Cambridge Journals Digital Archives
    Topics: History , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Centaurus 18 (1974), S. 0 
    ISSN: 1600-0498
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 3697-3705 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stable Copper and Silver Derivatives of Phosphorus YlidesTrimethylmethylenephosphorane has been shown to form an ionic 2:1 complex with (CH3)3PCuCl, of the formula [(CH3)3PCH2CuCH 2P(CH3)3]Cl (1). With (CH3)3SiCH2Cu, the molecular species (CH3)3SiCH2CuCH2P(CH3)3 (4) has been isolated, while with CuCl a novel eight-membered heterocycle [(CH3)2P(CH2)2Cu]2 (5)ist formed in a trans-ylidation reaction. The composition and structure of these unusual organocopper compounds have been proved by analytical and spectroscopic methods. The crystal structure of compound 5 has been determined elsewhere. - A silver analogue of 5 (6) is obtained from (CH3)3PAgCl (or AgCl) and (CH3)3PCH2. The detection of 1H-C-107, 109Ag and 31P-C-107,109Ag spin-spin-interactions in the n. m. r. spectra of 6 provided direct evidence for covalent C-Ag bonding in these molecules. The ylides C6H5(CH3)2PCH2 and CH3(C6H5)2PCH2 are forming similar Cu- and Ag-heterocycles (7a, b, 8a, b), but these compounds are of a markedly reduced thermal and chemical stability if compared with 5 and 6.
    Notes: Trimethylmethylenphosphoran bildet mit (CH3)3PCuCl einen ionogenen 2:1-Komplex der Formel [(CH3)3PCH2CuCH 2P(CH3)3]Cl (1), mit (CH3)3SiCH2Cu die Molekülverbindung (CH3)3SiCH2CuCH 2P(CH3)3 (4) und mit CuCl unter Umylidierung den neuartigen achtgliedrigen Heterocyclus [(CH3)2P(CH2)2Cu]2 (5). Die Zusammensetzung und Konstitution dieser kupferorganischen Verbindungen mit stabilisierendem Oniumzentrum wurden mit analytischen und spektroskopischen Methoden sichergestellt. Für 5 liegt von anderer Seite eine Röntgenstrukturanalyse vor. - Aus (CH3)3PCH2 und (CH3)3PAgCl entsteht nur die zu 5 analoge Silberverbindung 6, in deren NMR-Spektren die über echte Ag-C-σ-Bindungen vermittelten Spin-Spin- Wechselwirkungen 1H-C-107,109Ag und 31P-C-107,109Ag beobachtet werden können. Auch die Ylide C6H5(CH3)2PCH2 und CH3(C6H5)2PCH2 bilden derartige Cu- und Ag- Heterocyclen, die jedoch im Gegensatz zu 5 und 6 nur geringe thermische und chemische Beständigkeit aufzuweisen haben (7a, b, 8a, b).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 407 (1974), S. 109-118 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of the Selenospinel Formation by Electrical Conductivity MeasurementsThe formation of selenospinels ZnCr2Se4 and CdCr2Se4 by solid state reaction of ZnSe, CdSe and Cr2Se3 was investigated by electrical conductivity measurements. The conductivity measurements carried out at linearly increasing temperature of the reaction mixtures gave typical "glow" curves having maxima and minima, from which the formation of selenospinels was observed. The energy of activation of the selenospinels formation reaction was determined using the equations described by Lutz, considering shifts of conductivity maxima or minima towards higher temperatures. Some processes of selenospinels formation, e.g. the backward reactions, are discussed.
    Notes: Mit Hilfe von Leitfähigkeitsmessungen wurde die Bildung der Selenospinelle ZnCr2Se4 und CdCr2Se4 bei der Festkörperreaktion von ZnSe, CdSe und Cr2Se3 untersucht. Aus den Untersuchungen der elektrischen Leitfähigkeit bei zeitlinearer Aufheizung des Reaktionsgemisches erhielten wir typische „Glowkurven“ mit einem Leitfähigkeitsmaximum und -minimum, aus welchen der Verlauf der Selenospinellbildung beobachtet wurde. Aus den zu höheren Temperaturen verschobenen Leitfähigkeitsmaxima oder -minima wurde auf Grund der von Lutz beschriebenen Gleichung die Aktivierungsenergie der Selenospinellbildungsreaktion bestimmt. Weiter wurden einige im Prozeß der Selenospinellbildung auftretende Probleme, z. B. der Reaktion in rückläufiger Richtung, diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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