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  • 1
    ISSN: 0044-2313
    Keywords: Lanthanides ; hydride selenides ; preparation ; crystal structures ; 1H- and 2H-type MHSe ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: MHSe: Die ersten Hydridselenide der Lanthanide (M = La—Nd; Gd—Er, Lu)Durch Oxidation von Dihydriden (MH2) der meisten Lanthanide (M = La—Nd; Gd—Er, Lu) mit äquimolaren Mengen an Selen lassen sich die ersten Lanthanid-Hydridselenide (MHSe) gewinnen. Der Zusatz von Alkalichlorid (z. B. NaCl oder CsCl) als Flußmittel erlaubt vollständige und schnelle Umsetzungen (7 d) bei 700-850°C in verschweißten Tantalkapseln (geschützt durch evakuierte Quarzglasampullen) sowie einkristalline Produkte (blaß bläulichgraue hexagonale Sälen oder Plättchen).Zwei unterschiedliche Kristallstrukturen wurden anhand von röntgenographischen Einkristalldaten am Beispiel von 2H—CeHSe (hexagonal, P63/mmc (Nr. 194), Z = 2; a = 406,36(4), c = 794,81(9) pm; R1 = 0,0365, wR2 = 0,0766) und 1H—HoHSe (hexagonal, P6m2 (Nr. 187), Z = 1; a = 381,56(3), c = 387,28(5) pm; R1 = 0,0140, wR2 = 0,0337) bestimmt. Nach Ausweis von Pulverdiffraktometerdaten kristallisieren die Hydridselenide MHSe mit M = La—Nd isotyp mit 2H—CeHSe, jene mit M = Gd—Er und Lu sind, wie YHSe, isostrukturell zu 1H—HoHSe.Beide Strukturen enthalten Wasserstoff in der Hälfte der trigonal-planaren Lücken innerhalb der dichtest gepackten Einfach-Schichten der Metalle. Diese Schichten ∞2[(M3+)(H-)3/3]2+ (a,β oder b,α) sind längs [001] alternierend mit dichtest gepackten Einfach-Schichten aus Se2- (C) gestapelt und allein die Stapelfolge entscheidet, ob eine „aufgefüllte“ WC-(C(a,β)C ≡ 1 H—MHSe) oder eine „aufgefüllte“ anti-NiAs-Struktur (C(a,β)C(b,α)C ≡ 2H—MHSe) resultiert.
    Notes: The oxidation of most of the lanthanide dihydrides MH2 (M = La—Nd; Gd—Er, Lu) with equimolar amounts of selenium results in the formation of the first lanthanide hydride selenides MHSe. The presence of alkali chlorides (e.g., NaCl or CsCl) as fluxes secures complete and fast reactions (7 d) at 700-850°C in sealed, arc-welded tantalum capsules (protected by evacuated silica vessels) as well as single-crystalline products (pale bluish-gray hexagonal columns or platelets).Two different structures were determined from X-ray single crystal data for the examples of 2H—CeHSe (hexagonal, P63/mmc (no. 194), Z = 2, a = 406.36(4), c = 794.81(9) pm, R1 = 0.0365, wR2 = 0.0766) and 1H—HoHSe (hexagonal, P6m2 (no. 187), Z = 1, a = 381.56(3), c = 387.28(5) pm, R1 = 0.0140, wR2 = 0.0337). According to X-ray powder data, the hydride selenides MHSe with M = La—Nd proved to be isostructural with 2H-CeHSe, those with M = Gd—Er and Lu crystallize isotypically with 1H—HoHSe just like YHSe.Both structures contain hydrogen in half of the trigonal planar interstices within closest-packed mono-layers of the metals. These layers ∞2[(M3+)(H-)3/3]2+ (a,β or b,α) are alternatively sheethed with closest-packed mono-layers of Se2- (C) along [001], and only the stacking sequence decides whether a “stuffed” WC- (C(a,β)C ≡ 1 H-MHSe) or a “stuffed” anti-NiAs-type arrangement (C(a,β)C(b,α)C ≡ 2H—MHSe) emerges.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1501-1502 
    ISSN: 0044-2313
    Keywords: Cesium yttrium selenide ; Cs3Y7Se12 ; rare-earth compounds ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Crystal Structure of Cs3Y7Se12The oxidation of yttrium metal with selenium in the presence of CsCl (7 d, 700°C, evacuated silicia tubes) results in the formation of pale yellow, lath-shaped single crystals of Cs3Y7Se12. The crystal structure (orthorhombic, Pnnm, Z = 2, a = 1272.8(3), b = 2627.7(5), c = 413.32(8) pm) consists of edge- and vertex-connected [YSe6] octahedra forming a rocksalt-related network [Y7Se12]3-. One-dimensional infinite channels along [001], apt to take up extra cations, provide coordination numbers of 6 and 7 + 1, respectively, for two crystallographically different Cs+.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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