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  • 1980-1984  (6)
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  • 1
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polarographic Behaviour of Molybdenum(VI) with Special Reference to the Reactions of Molybdenum(V)The reduction of molybdenum(VI) proceeds via molybdenum(V) to molybdenum(III) in sulfuric acid. A dimerization of the formed molybdenum(V) takes place according to a D-mechanism, if hydroxide ligands are involved. The rate of dimerization is large enough to influence the polarographic picture for cH2SO4 〈 2 mol · 1-1 considerably. No experimental reference could be obtained to the existence of molybdenum(IV) during polarography. It was shown, that the preparation of very unstable solutions containing monomeric paramagnetic molybdenum(V) complexes is possible.A summary of the chemical reactions is suggested.
    Notes: Die Reduktion von Molybdän(VI) führt in Schwefelsäure über Molybdän(V) zu Molybdän(III). Enthält das sich zunächst bildende monomere Molybdän(V) Hydroxidliganden, so erfolgt eine Dimerisierung nach dem D-Mechanismus. Diese Dimerisierung ist für cH2SO4 〈 2 mol · 1-1 so schnell, daß das polarographische Bild entscheidend durch diesen Prozeß geprägt wird. Während der Reduktion gibt es keine Hinweise für das Auftreten von Molybdän(IV). Unbeständige Lösungen monomerer paramagnetischer Molybdän(V)-Komplexe konnten erhalten werden.Ein zusammenfassendes Reaktionsschema wird vorgeschlagen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: EPR Studies of Caminau Kaolin, its Heating Products, and of the Chlorination Products of MetakaolinEPR-spectra of kaolin, metakaolin and of the heating and chlorination products of metakaolin have been measured and partially interpreted. Fe3+ ions are found in kaolin in at least five different coordination conditions. Coordination changes of Fe3+ ions by heating kaolin and tempering metakaolin are reflected sensitively in the EPR spectra. Correlations between EPR spectra of the solid not fluidable chlorination residues and chlorination conditions have been found.
    Notes: Es wurden die EPR-Spektren von Kaolin, Metakaolin sowie von dessen Temper- und Chlorierungsprodukten aufgenommen und z. T. interpretiert. Im Kaolin befinden sich Fe3+-Ionen in mindestens fünf verschiedenen Koordinationszuständen. Die beim Erwärmen des Kaolins, bei dessen Calcinierung sowie beim Tempern des Metakaolins eintretenden Veränderungen werden in den EPR-Spektren empfindlich widersgepiegelt. Zwischen den EPR-Spektren der festen Chlorierungsrückstände und den Chlorierungsbedingungen wurden Zusammenhänge gefunden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Effect of Different Oxidation States of Nickel and Chromium in Heterogenous Halogen ExchangeNi-doted AlF3 catalysts and chromium oxide fluoride catalysts being used for production of C—Cl—F compounds from chlorocarbons by reaction with HF have been investigated by EPR. There are different oxidation states of Ni resp. Cr at the catalysts which show exchange behaviour. Extending the consumptions of mechanisms for heterogeneous Cl—F exchange the oscilation of oxidation state and therefore the exchange in donor-acceptor functions at the catalysts is said to be the cause for the effectiveness of the catalysts. It is presumed that this exchange of oxidation states is of general importance for catalytic processes with heterolytic bond cleavage.
    Notes: Mit der Hilfe von EPR-Messungen wird an Ni-beladenen AlF3-Katalysatoren die Gegenwart von Ni3+ neben chemisch nachgewiesenem Ni2+ und an Chromoxid-Gel-Katalysatoren die Austauschwechselwirkung zwischen CrIII und höheren Oxydationsstufen des Chroms aufgezeigt. Beide Katalysatortypen sin zur Herstellung von C—Cl—F-Verbindungen aus Kohlenstoffchloriden mittels HF geeignet. In Erweiterung von Vorstellungen zum Mechanismus des heterogen-katalytischen Cl—F-Austauschs wird die Oszillation der Oxydationsstufen and damit der Wechsel in Donor-Akzeptor-Funktionen am Katalysator für die Effektivität der Katalysatoren verantwortlich gemacht. Es wird auf die allgemeine Bedeutung dieses Mechanismus hingewiesen.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 515 (1984), S. 230-240 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Existence and Structure of Secondary DithizonatesOn example of complexation with copper and palladium proved, that dithizone by double deprotonation forming neutral “secondary” dithiozonates, which have been characterized by elemental analyses, electronic, i.r., ESCA, and EPR spectra and magnetic measurements. Dithizone reacts about ligator atoms N,N′,S. Secondary dithizonates probable are present dimeric.
    Notes: Am Beispiel der Komplexbildung mit Kupfer und Palladium wird nachgewiesen, daß Dithizon unter zweifacher Deprotonierung neutrale, „sekundäre“ Dithizonate bildet, die durch Elementaranalyse, VIS-, IR-, EPR- und Photoelektronen-Spektren sowie magnetische Messungen charakterisiert werden. Dithizon wirkt über die Ligatoratome N,N′,S. Die sekundären Dithizonate liegen wahrscheinlich dimer vor.
    Additional Material: 2 Ill.
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  • 5
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations about the Structure of Copper Complexes from 2,4-Dichlorphenoxyacetic Acid
    Additional Material: 2 Ill.
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  • 6
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Determination of the Zero Field Parameters Optically Excited 3(π,π*)-States in Selected Aromatic SystemsExperimental zero field parameters of optically excited naphthalene and quinoxaline derivatives are presented. The (D*), (D) and (E) parameters are determined by the position of the transitions by means of simple approximation formula, magnetophotoselection and simulation of spectra. Possibilities of comparison of the zero field parameters of optically excited 3(π,π*)-states with parameters of ground state for simple aromatic hydrocarbones are presented.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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