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  • Chemistry  (2)
  • Vibrational Spectra  (1)
  • 1
    ISSN: 0044-2313
    Keywords: Alkali metal germanides and stannides ; Zintl cluster anions ; Vibrational spectra ; Thermal decomposition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binary germanides M12Ge17 and M4Ge9 (M = Na, K, Rb, Cs) and the stannides M12Sn17 and M4Sn9 (M = K, Rb, Cs) were identified by a combination of direct synthesis, thermogravimetric analysis, vibrational spectroscopy, X-ray powder data and single crystal structure analysis. The M12E17 phases contain the cluster anions [E9]4- and [E4]4- in the ratio 1:2, forming a hierarchical structure with the cluster anions at the atomic positions of the hexagonal Laves phase MgZn2. Like the M4E4 phases, the M4Ge9 compounds are hierarchical derivatives of the cubic Cr3Si structure but with [Ge9]4- anions. The thermogravimetric analyses give strong evidence for the existence of at least one more phase with [E9]4- and [E4]4- clusters and of the clathrate phases M6E136 in addition to the well-known M8E44□2 chlathrates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Ba3Ge4C2 ; Zintl Phase ; tetrahedro-Tetragermanide [Ge4]4- Anions ; Acetylenide [C2]2- Anions ; Vibrational Spectra ; Force Constants ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tribarium tetrahedro-Tetragermanid- Acetylenid, Ba3[Ge4][C2] - Synthese, Struktur und EigenschaftenBa3Ge4C2 bildet sich aus den Elementen order durch die Umsetzung von BaC2 mit BaGe2 bei 1530 K (korundtiegel in geschlossener Stahlampulle). Die Verbindung ist ein Halbleiter (grau; Eg = 1.1 eV), spröde, und sehr feuchtigkeitsempfindlich. Sie reagiert mit NH4Cl bei ca. 400 K unter Bildung von Acetylen und Germanen bis Ge4Hn. Der neue Ba3Ge4C2-Strukturtyp (Raumgruppe I4/mcm, No. 140; a = 8.840(1) Å, c = 12.466(1) Å; Z = 4, Pearsonsymbol tI36) enthält zwei isolierte Polyanionen, nämlich Tetrahedro-tetragermanid [Ge4]4- und Acetylenid [C2]2-. Die Bindungslängen betragen d(Ge—Ge) = 2.517 Å (4×) bzw. 2.641 Å (2x) und d(C≡C) = 1.20 Å. Die Struktur von Ba3[Ge4][C2] ist durch Atom/Cluster-Substitutionen ([Ge4] statt Ca; [C2] statt Ti; Ba statt O) eine hierarchische Variante der Perowskit-Struktur CaTiO3. Das Raman-Spektrum zeigt Banden bei 168, 199 und 280 cm-1 bzw. 1796 cm-1, die für die Polyanionen [Ge4]4- und [C2]2- charakteristisch sind.
    Notes: Ba3Ge4C2 is formed at 1530 K from the elements or by reaction of BaC2 with BaGe2 (corundum crucible; steel ampoule). The compound is a semiconductor (grey colour; Eg = 1.1 eV), brittle, very sensitive to moisture, and reacts with NH4Cl at about 400 K forming acetylene and germanes up to Ge4Hn. The new Ba3Ge4C2 structure type (space group I4/mcm, No. 140; a = 8.840(1) Å, c = 12.466(1) Å; Z = 4, Pearson code tI36), contains two kinds of isolated polyanions, namely tetrahedro-tetragermanide [Ge4]4- and acetylenide [C2]2- anions. The bond lengths are d(Ge-Ge) = 2.517 Å (4×) and 2.641 Å (2×), and d(C≡C) = 1.20 Å. The Ba3[Ge4][C2] structure is a hierarchical derivative of the perovskite (CaTiO3) generated by a partial atom/cluster replacement ([Ge4] for Ca, [C2] for Ti and Ba for O). The Raman spectrum shows bands at 168, 199 and 280 cm-1, and at 1796cm-1 characteristic for [Ge4]4- and [C2]2- polyanions, respectively.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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