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  • 1
    ISSN: 0044-2313
    Keywords: Rare Earth Elements ; Halides ; Clusters ; Cesium Scandium Chloride Carbide ; Cesium Praseodymium Iodide Dicarbide ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cs4[Sc6C]Cl13 and Cs4[Pr6(C2)]I13  -  Two Examples for the Missing Link in the Connectivity of [M6Z]X12iX6a Building UnitsCs4[Sc6C]Cl13 (tetragonal, I41/amd, a = 1 540.5(4), c = 1 017.9(7) pm, c/a = 0.661, Z = 4, R = 0.038, Rw = 0.026) and Cs4[Pr6(C2)]I13 (a = 1 804.9(3), c = 1 259.5(3) pm, c/a = 0.698, R = 0.106, Rw = 0.068) are obtained as green-black and blue-black single crystals with brass-like metallic lustre through metallothermic reduction of ScCl3 and PrI3, respectively, with cesium in the presence of carbon in sealed tantalum containers. The, overall, isotypic compounds contain isolated [Sc6C] and [Pr6(C2)] clusters, respectively, that are surrounded by 18 halide (X) ligands (12 Xi and 6 Xa; X = Cl or I). The connection is carried out via the motif [M6Z]X8iX4/21-aX4/2a-1X2/2a-a (M = Sc and Pr; Z = C and C2, respectively) and is thereby the missing link of the motifs of connection for the composition Ax[M6Z]X13. Analogous interconnection of [TiO6] octahedra is found in the anatase-type of structure of TiO2.
    Notes: Cs4[Sc6C]Cl13 (tetragonal, I41/amd; a = 1 540,5(4); c = 1 017,9(7) pm; c/a = 0,661; Z = 4; R = 0,038; Rw = 0,026 und Cs4[Pr6(C2)]I13 (a = 1 804,9(3); c = 1 259,5(3) pm; c/a = 0,698; R = 0,106; Rw = 0,068) werden bei der metallothermischen Reduktion von ScCl3 bzw. PrI3 mit Caesium in Gegenwart von Kohlenstoff in verschweißten Tantalampullen in Form von grünschwarzen bzw. blauschwarzen, messingglänzenden Einkristallen erhalten. Die weitgehend isotypen Kristallstrukturen enthalten isolierte [Sc6C]- bzw. [Pr6(C2)]-Cluster, die von 18 Halogenid-Ionen (X-, 12 Xi und 6 Xa; X = Cl bzw. I) umgeben sind. Die Verknüpfung erfolgt gemäß dem Motiv [M6Z]X8iX4/21-aX4/2a-1X2/2a-a (M = Sc bzw. Pr; Z = C bzw. C2) und stellt damit ein noch unbekanntes Verknüpfungsmuster für Verbindungen der Zusammensetzung Ax[M6Z]X13 dar, das jenem der [TiO6]-Oktaeder in der Anatas-Struktur von TiO2 entspricht.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 618 (1992), S. 7-12 
    ISSN: 0044-2313
    Keywords: Metallothermic Reduction ; Dibromides ; Diiodides ; Thulium ; Ytterbium ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metallothermic Reduction of the Tribromides and -iodides of Thulium and Ytterbium with Alkali MetalsMetallothermic reduction of the trihalides MX, (M = Tm, Yb; X = Br, I) with equimolar amounts of alkali metal (A = Li—Cs; 700-800°C, 7 d, tantalum capsules) results in the formation of the dihalides MX, (MI, with the Cd1,-type of structure, MBr, with the SrI2- or α-PbO2-type of structure) in the case of lithium and sodium. With A = K, Rb, Cs variants of the perovskitetype structure with the composition AMX, are obtained. They crystallize with the undistorted cubic CaTiO3-type (CsYbBr3), with the tetragonal NaNbO3-11-type (CsTmBr3) or with the orthorhombic GdFeO3-type (CsMI3, RbMX3 and KMBr3). In KTmI, and KYbI3, corner- and edge-connected [MI6] octahedra form layers which are connected via K+ in analogy to a stuffed PuBr3- or the FeUS3-type structure (orthorhombic, Cmcm). Single crystals of Rb4YbI6 are obtained as a by product upon the reduction of YbI3 with rubidium. According to their K4CdCl6-type structure (trigonal, R3c), isolated [YbI6] octahedra are the main structural feature.
    Notes: Bei der metallothermischen Reduktion der Trihalogenide MX3 (M = Tm, Yb; X = Br, I) mit äquimolaren Mengen an Alkalimetall (A = Li—Cs; 700-800°C, 7 d, Tantalampullen) werden im Falle von Lithium und Natrium die Dihalogenide MX2 erhalten (MI2 im CdI2-Typ, MBr2 im SrI2-bzw. α-PbO2-Typ). Mit A = K, Rb, Cs entstehen Perowskitvarianten AMX3, die im unverzerrten kubischen CaTiO3-Typ (CsYbBr3), im tetragonalen NaNbO3-II-Typ (CsTmBr3) bzw. im orthorhombischen GdFeO3-Typ (CsMI3, RbMX3 und KMBr3) kristallisieren. Bei KTmI3 und KYbI3 treten ecken- und kantenverknüpfte [MI6]-Oktaeder auf, die Schichten bilden und durch K+ analog einer aufgefüllten PuBr3- bzw. der FeUS3-Struktur (orthorhombisch, Cmcm) zusammengehalten werden. Als Nebenprodukt bei der Reaktion von YbI3 mit Rubidium erhält man Einkristalle von Rb4YbI6 im K4CdCl6-Typ (trigonal, R3c), in dem isolierte [YbI6]-Oktaeder vorliegen.
    Additional Material: 2 Ill.
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