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  • 1
    ISSN: 0947-3440
    Keywords: Peterson olefination ; Horner Emmons olefination ; Diastereoselective aprotic Michael cascade reaction ; Tricyclo[3.2.1.02,7]octanes ; Bicyclo[3.2.1]octanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from the easily accesible chiral aldehyde 2, we obtained enantiomerically pure (Z)- and (E)-α,-chloro-α,β-unsaturated esters 4c in good yields by olefination reactions. (Z)-and (E)-4c were allowed to react with the kinetically controlled generated lithium dienolate Li-7 to give the enantiomerically pure tricyclo[3.2.1.02,7]octanes 8 and 9, respectively. The „push-pull“ substituted cyclopropane moiety of 8 was opened to give solely bicyclo[3.2.1]octane 10.
    Type of Medium: Electronic Resource
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  • 2
    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.
    Type of Medium: Electronic Resource
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