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  • Articles: DFG German National Licenses  (3)
  • Apocynaceae  (1)
  • Bromozincates  (1)
  • Halogenocyclotetraphosphanes  (1)
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  • Articles: DFG German National Licenses  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 21 (1982), S. 1585-1588 
    ISSN: 0031-9422
    Keywords: Apocynaceae ; Catharanthus roseus ; biosynthesis ; cell suspension culture. ; geissoschizine dehydrogenase ; heteroyohimbine alkaloids ; stereospecificity
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 993-998 
    ISSN: 0044-2313
    Keywords: Bromozincates ; zinc ; olivine-type halides ; neutron diffraction ; fast ionic conductivity ; Raman spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Halogenozincates M2IZnX4 (MI = Li, Na; X = Cl, Br) of Olivine TypeThe hitherto unknown tetrabromozincates Li2ZnBr4 and Na2ZnBr4 have been prepared. Quaternary halides Li2Zn(Cl, Br)4 and Li2Zn(Br, I)4 have been not obtained due to decomposition to mixtures of LiCl and ZnBr2, and LiBr and ZnI2. The crystal structures of the olivine-type bromides and of the high-temperature polymorph of Li2ZnCl4 have been determined by neutron powder diffraction using the Rietveld method (space group Pnma, Z = 4, a = 1 360.41(4), b = 788.47(2), c = 647.07(2) pm, RI = 9.07% (Li2ZnBr4), a = 1 446.32(5), b = 853.02(3), c = 676.61(2) pm, RI = 9.29% (Na2ZnBr4), a = 1 277.60(3), b = 741.76(2), c = 611.10(1) pm, RI = 7.63% (Li2ZnCl4)). The Raman spectra as well as the results of thermal analyses (DSC) and conductivity measurements (impedance spectroscopy) are presented and discussed. Contrary to Li2ZnCl4, Li2ZnBr4 and Na2ZnBr4 do not undergo any phase transition between 20°C and their melting points.
    Notes: Die Darstellung der bisher nicht bekannten Tetrabromozinkate Li2ZnBr4 und Na2ZnBr4 wird beschrieben. Quaternäre Halogenide des Typs Li2Zn(Cl, Br)4 bzw. Li2Zn(Br, I)4 konnten nicht erhalten werden. Es erfolgt Entmischung zu LiCl und ZnBr2 bzw. LiBr und ZnI2. Die Kristallstrukturen der im Olivintyp kristallisierenden Bromide und der Hochtemperaturform von Li2ZnCl4 wurden auf der Basis von Neutronenpulver-Messungen nach der Rietveld-Methode bestimmt (Raumgruppe Pnma, Z = 4, a = 1 360,41(4), b = 788,47(2), c = 647,07(2) pm, RI = 9,07% (Li2ZnBr4), a = 1 446,32(5), b = 853,02(3), c = 676,61(2) pm, RI = 9,29% (Na2ZnBr4), a = 1 277,60(3), b = 741,76(2), c = 611,10(1) pm, RI = 7,63% (Li2ZnCl4)). Raman-Spektren sowie das Ergebnis thermoanalytischer Untersuchungen (DSC) und Leitfähigkeitsmessungen (Impedanz-Spektroskopie) werden mitgeteilt. Li2ZnBr4 und Na2ZnBr4 zeigen im Gegensatz zu Li2ZnCl4 zwischen 20°C und dem Schmelzpunkt keine Phasenumwandlung.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Phosphanediyl ; Halogenocyclotetraphosphanes ; NMR Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: In situ Generation of [PX] and Insertion into (tBuP)3, (X = Cl, Br). Synthesis of the Functionalized Cyclophosphanes (tBuP)3PX, [1-(tBu)(X)P-2,3,4-(tBu)3]P4 and Structure Analysis of (tBuP)3PClThe redox system PX3/SnX2 (X = Cl, Br) can be used as a source for the in situ generation of halogenphosphanediyl [PX]. In the presence of tri-t-butylcyclotriphosphane (tBuP)3 the intermediately formed [PX] is added to a ring P atom followed by an insertion reaction, which leads to a ring expansion, whereby monohalogenocyclotetraphosphanes (tBuP)3PX (X = Cl, Br; 1, 2) are formed. Excess [PX] does not lead to further ring expansion but through a complex reaction course to the functionalized cyclotetraphosphanes [1-(tBu)(X)P-2,3,4-(tBu)3]P4, 3 (X = Br); 7 (X = Cl). 1, 2 and 3 could be obtained in a pure form and NMR and mass spectroscopically, 7 31P-NMR spectroscopically, characterized. For 1 and 7 31P—35,37Cl-isotopic shifts could be identified. 1 was further characterized by an X-ray structure analysis.
    Notes: Das Redoxsystem PX3/SnX2 (X = Cl, Br) kann als Quelle zur in situ-Bildung von Halogenphosphandiyl [PX] verwendet werden. In Gegenwart von Tri-t-butylcyclotriphosphan (tBuP)3 wird intermediär auftretendes [PX] zuerst an ein Ring-P-Atom addiert, dann unter Ringexpansion insertiert, wobei Monohalogenocyclotetraphosphane (tBuP)3PX (X = Cl, Br; 1, 2) gebildet werden. Überschüssiges [PX] führt nicht zu einer weiteren Ringexpansion; vielmehr entstehen in einem komplexen Reaktionsverlauf die funktionalisierten Cyclotetraphosphane [1-(tBu)(X)P-2,3,4-(tBu)3]P4, 3 (X = Br); 7 (X = Cl). 1, 2 und 3 konnten in reiner Form isoliert und NMR- sowie massenspektroskopisch, 7 31P-NMR-spektroskopisch, charakterisiert werden. Bei 1 und 7 konnten 31P—35,37Cl-Isotopieverschiebungen nachgewiesen werden. Von 1 wurde eine Röntgenstrukturanalyse durchgeführt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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