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  • 1
    Electronic Resource
    Electronic Resource
    Struktur und thermisches Verhalten von Gadolinium(III)-sulfat-Octahydrat Gd2(SO4)3 · 8 H2O (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 805-810 
    Details
    ISSN: 0044-2313
    Keywords: Gadolinium compounds ; preparation ; crystal structures ; DTA-TG analysis ; X-ray powder pattern ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure and Thermal Behaviour of Gadolinium(III)-sulfate-octahydrate Gd2(SO4)3 · 8 H2O.Gd2(SO4)3 · 8 H2O crystallizes monoclinic with space group C2/c and the lattice constants a = 13.531(7), b = 6.739(2), c = 18.294(7) Å, β = 102.20(8)°. In the structure Gd is coordinated by 4 oxygen atoms of crystal water and 4 oxygens of sulfate giving rise to a distorted square antiprism. During DTA-TG-experiments the title compound first loses crystal water in a two-step mechanism in the temperature range 130-306°C. The resulting Gd2(SO4)3 is amorphous and recrystallization occurs in the range 380-411°C. The so-obtained low-temperature modification β-Gd2(SO4)3, undergoes a monotropic phase transition at about 750°C to the high-temperature form α-Gd2(SO4)3. The powder pattern of this modification was indexed based on monoclinic symmetry with space group C2/c and lattice constants a = 9.097(3), b = 14.345(5), c = 6.234(2) Å, β = 97.75(8)°. The hightemperature modification of gadolinium-sulfate shows decomposition to Gd2O2SO4 at 900°C and, subsequently, decomposition at 1 200°C yields the formation of C-Gd2O3.
    Notes: Gd2(SO4)3 · 8 H2O kristallisiert monoklin in der Raumgruppe C2/c mit den Gitterkonstanten a = 13,531(7), b = 6,739(2), c = 18,294(7) Å und β = 102,20(8)°. In der Struktur ist Gd von je 4 Sauerstoffatomen des Hydratwassers und der Sulfationen in Form eines stark verzerrten quadratischen Antiprismas umgeben. Im DTA-TG-Experiment verliert Gd2(SO4)3 · 8 H2O in einem zweistufigen Prozeß im Temperaturbereich 130-306°C zunächst Kristallwasser; anschließend tritt zwischen 380 und 411°C Rekristallisation des amorphen Gd2(SO4)3 unter Bildung der Tieftemperaturmodifikation β-Gd2(SO4)3 auf. Bei ca. 750°C wird monotrop die Hochtemperaturmodifikation α-Gd2(SO4)3 gebildet. Aus der Analyse der Pulverdaten folgt monokline Symmetrie mit der Raumgruppe C2/c und den Gitterkonstanten a = 9,097(3), b = 14,345(5), c = 6,234(2) Å und β = 97,75(8)°. Ab ca. 900°C beginnt die Zersetzung von α-Gd2(SO4)3 zu Gd2O2SO4 und ab 1 200°C liegt C-Gd2O3 vor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190429
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  • 2
    Electronic Resource
    Electronic Resource
    Neue dimere Goldselenolate: Darstellung und strukturelle Charakterisierung von [(n-C4H9)4N]2[AuSSeC=C(CN)2]2 und [(n-C4H9)4N]2[AuSe2C=C(CN)2]2Herrn Professor Wolfgang Beck zum 60. Geburtstage gewidmet (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 611 (1992), S. 81-84 
    Details
    ISSN: 0044-2313
    Keywords: Gold complexes ; preparation ; crystal structures ; ab initio Hartree-Fock calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Dimeric Gold Selenolates: Preparation and Characterization of [(n-C4H9)4N]2[AuSSeC = C(CN)2]2 and [(n-C4H9)4N]2[AuSe2C = C(CN)2]2The preparation and structural characterization of the dimeric AuI complexes of 1,1-dicyanoethene-2,2-thioseleonlate (i-mnts) and 1,1-dicyanoethene-2,2-diselenolate (i-mns), isolated as Bu4N salts, are described. They are isotype (monoclinic, space group P21/c, Z = 2) with lattice parameters: (Bu4N)2[Au(i-mnts)]2; a = 14.078(3) Å, b = 8.912(3) Å, c = 20.142(4) Å, β = 106.32(5)°; (Bu4N)2[Au(i-mns)]2; a = 13.998(3) Å, b = 9.125(3) Å, c = 20.039(2) Å, β = 105.12(5)°. Ab initio Hartree-Fock calculations based on the experimentally determined structure yield a positive value of the Au—Au bonding order suggesting weak bonding interactions between the d10 metal centres.
    Notes: Die Darstellung und Strukturaufklärung der als Bu4N-Salze (Bu = n-C4H9) isolierten dimeren AuI-Komplexe des 1,1-Dicyanoethen-2,2-thioselenolats (i-mnts) und des 1,1-Dicyanoethen-2,2-diselenolats (i-mns) werden beschrieben. Sie kristallisieren zueinander isotyp (monoklin, Raumgruppe P21/c, Z = 2) mit folgenden Gitterkonstanten: (Bu4N)2[Au(i-mnts)]2; a = 14,078(3) Å, b = 8,912(3) Å, c = 20,142(4) Å β = 106,32(5)°; (Bu4N)2[Au(i-mns)]2; a = 13,998(3) Å, b = 9,125(3) Å, c = 20,039(2) Å, β = 105,12(5)°. Ab-initio-Hartree-Fock-Rechnungen unter Zugrundelegung der experimentell bestimmten Geometrie mit Kristallfeldsimulation liefern einen positiven Wert der Au—Au-Bindungsordnung, der darauf hindeutet, daß der kurze Au—Au-Abstand (2,810(1) äR) auf schwache bindende Wechselwirkungen zwischen den d10-Metallzentren zurückgeführt werden kann.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926110513
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