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  • Chalcogenoboron hydride structure  (1)
  • Crystal growth  (1)
  • Gadolinium Bromide Carbide Nitride  (1)
  • Wiley-Blackwell  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1235-1240 
    ISSN: 0009-2940
    Keywords: Phosphorus ; Phase transitions ; Molecular crystal ; Crystal growth ; Low-temperature crystal structure ; Librational motion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: White phosphorus occurs in three modifications. The α form, which exists at roomtemperature, transforms reversibly to the β form at -77°C. The α · β transformation may be strongly delayed. Quenching the α form to -185°C followed by slow warming results in an exothermic reactions with formation of the γ form which transforms into the β form at -120°C in an endothermic reaction. A transition β · γ is not observed. The γ form is characterized by its powder diagram. The structure of the β form is redetermined from a single crystal at -185°C (P., α = 547.88(5), b = 1078.62(11), c = 1096.16(11)pm, α= 94.285(8), β = 99.695(7), γ = 100.680(7)., V = 623.79(10) · 106 pm3, Z = 6 formula units per cell). The P4 molecules exhibit pronounced librational motion in spite of the low temperature of investigation. The arrangement of the centers of the tetrahedra corresponds to the atom positions in the γ-plutonium structure, which is discussed in relation to the bcc structure.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 427-432 
    ISSN: 0009-2940
    Keywords: Chalcogenoboron hydride structure ; Adamantane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [(BH6)2]S4]2-, [(BH2)Se4]2-: New Chalcogenoboron Hydride Anions with Adamantane StructureThe reaction of THF·BH3/NaBH4 (2: 1) with H2S produces Na[H3B-μ2-S(B2H5)] (5) with hydrogen evolution. 5 reacts with an excess of H2S to give Na2[(BH2)6S4] (3a), which is also formed in the reaction of THF·BH3 with NaSH or anhydrous Na2S. These reactions proceed via 5 and the intermediates 7 or 8 by loss of BH-4 and cyclization. The analogous compound Na2[(BH2)6Se4] (4a) is obtained by the reaction of elemental selenium with NaBH4 (1:1) in triglyme. The primary product is Na2[H3B-Se-Se-BH3] (9). Treatment of 9 at 100 - 110°C yields 4a and polymers, 3a and 4a react with CsBr to form the crystalline compounds Cs2[(BH2)6Se4]·CsBr (3b) and Cs2-[(BH2)6Se4]·CsBr (4b), characterized by X-ray structure determinations. The anions of 3b and 4b consist of an adamantane skeleton. The Br- ion is octahedrally coordinated by Cs+ ions. The Cs6Br octahedra share faces to form columns along the hexagonal c axis. The crystal structures of the isotypic compounds 3b and 4b are closely related to the structure of CsNiCl3.
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Gadolinium Iodide Carbide Nitride ; Gadolinium Bromide Carbide Nitride ; Yttrium Iodide Carbide Nitride ; Lanthanum Iodide Carbide Nitride ; preparation ; X-ray single crystal structure investigation ; crystal structure ; condensed cluster ; chain of condensed octahedra and double tetrahedra ; C—C single bond ; Gd6(C2) octahedron ; Gd6N2 double tetrahedron ; Y10(C2)2 double octahedron ; Y6N2 double tetrahedron ; α-Gd4I6CN, β-Gd4I6CN, Y6I9C2N, α-Gd4Br6CN, α-La4I6CN ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gd4I6CN: A Carbide Nitride with Chains of Gd6(C2) Octahedra and Gd6N2 Double TetrahedraThe compound α-Gd4I6CN is prepared by reaction of Gd, GdI3, C, and GdN (1:2:1:1 mole ratio) at 1 170 K in sealed Ta tubes. It is obtained as brown red, transparent needles which are air and moisture sensitive. The structure of α-Gd4I6CN contains Gd6 octahedra centered by C2 groups and double tetrahedra centered by N atoms. The units are alternatingly connected via common edges to form chains (Gd2Gd4/2C2) (Gd2/2Gd2/2N)2 parallel [001]. The linear chains are surrounded by I atoms above all free edges of the metal polyhedra and linked according to (Gd2Gd4/2C2) (Gd2Gd4/2N2)I4/2I8I2 in the a - b plane.We also found β-Gd4I6CN, which is formed in a monotropic transition from the α-form. In the structure the chains of Gd octahedra and tetrahedra as described for α-Gd4I6CN are more densely packed.The structure of Y6I9C2N is composed by chains of pairs of Y-octahedra and Y-tetrahedra, respectively. The octahedra are centered by C2 groups, the tetrahedra by N-atoms.We also synthesized the compounds Gd4Br6CN und La4I6CN by tempering at 1 220 K. They are isotypic with α-Gd4I6CN.
    Notes: α-Gd4I6CN wird durch Reaktion von Gd, GdI3, C und GdN (Molverhältnis 1:2:1:1) bei 1 170 K im verschlossenen Ta-Tiegel erhalten. Es bildet braunrot durchscheinende Nadeln, die gegen Luft und Feuchtigkeit empfindlich sind. Die Struktur von α-Gd4I6CN enthält durch C2-Einheiten zentrierte Gd6-Oktaeder und Doppel aus N zentrierten Tetraedern, Gd6N2. Abwechselnd sind Oktaeder und Tetraederdoppel über gemeinsame Kanten zu Ketten (Gd2Gd4/2C2) (Gd2/2Gd2/2N)2 verknüpft, die parallel [001] ausgerichtet sind. Diese eindimensionalen Einheiten sind über allen freien Kanten durch Iodatome koordiniert und untereinander nach dem Schema (Gd2Gd4/2C2) · (Gd2Gd4/2N2)I4/2I8I2 in der a - b-Ebene verknüpft.Daneben existiert noch ein β-Gd4I6CN, das sich monotrop aus der α-Form bei 1 300 K bildet. Dessen Struktur zeichnet sich durch eine dichtere Packung der für die α-Form beschriebenen Gd-Oktaeder-Tetraederketten aus.In der Struktur von Y6I9C2N sind die Ketten aus Doppeln sowohl C2-zentrierter Oktaeder als auch N-zentrierter Tetraeder der Y-Atome aufgebaut.Weiter erhielten wir die mit α-Gd4I6CN isotypen Verbindungen Gd4Br6CN und La4I6CN durch Tempern der Ausgangsverbindungen bei 1 220 K.
    Additional Material: 6 Ill.
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