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  • crystal structure  (3)
  • 1995-1999  (3)
  • 1
    ISSN: 0947-6539
    Keywords: crystal structure ; cyclobutenes ; nickel ; radialenes ; radical reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of hexakis(dibromomethyl)benzene with [(Bu3P)2-Ni(COD)] (COD = 1,5-cyclooctadiene) in DMF at 65-70°C yielded a mixture of the title compounds. The mixture was separated by column chromatography to yield hexabromotricyclobutabenzene (3 a) and hexabromohexaradialene (4) in 24 and 16% yields, respectively. 1H and 13C NMR spectroscopy suggest that 3 is obtained as the syn-all-trans isomer 3 a, and the symmetric anti-all-trans isomer 3 b is not obtained at all. The X-ray structures of 3 a and 4 are reported. The hexaradialene 4 has a chair conformation, and deviates from planarity by 43.6°. Heat or radical impurities cause the clean transformation of 3 a to 4.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Decaisopropylstannocene ; crystal structure ; CPMAS 119Sn NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Meso- and Rac-Decaisopropylstannocene: Stereoisomerism Caused by Parallel Arrangement of Two Pentaisopropylcyclopentadienyl Ligands in Paddlewheel ConformationDecaisopropylstannocene 1 is the first Decaisopropylmetallocene, where X-ray diffraction data could be successfully refined and the third example of a group 14 Metallocene with a symmetric sandwich structure. Due to the directionality of the isopropyl substituents 1 occurs as a mixture of diastereomers in the crystalline state as well as in solution. The stereoisomers exhibit the expected signals in solution (1H and 13C NMR) and in the crystal (CPMAS 119Sn NMR).
    Notes: Decaisopropylstannocen 1 ist das erste Decaisopropylmetallocen, dessen Röntgendiffraktometer-Datensatz erfolgreich verfeinert werden konnte und das dritte Beispiel eines Metallocens der Gruppe 14 mit einer symmetrischen Sandwichstruktur. Aufgrund der Direktionalität der Isopropylsubstituenten beider Ringliganden liegt 1 im Kristall und in Lösung als Diastereomerengemisch vor. Die Stereoisomeren zeigen die erwarteten Signale in Lösung (1H- und 13C-NMR) und im Kristall (CPMAS- 119Sn-NMR).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Pentafluorobenzenesulfanylamines ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktionen der Pentafluorobenzolsulfanylamine (C6F5S)nNH3-n, n = 1, 2, 3 und Struktur des (C6F5S)3NAusgehend von (C6F5S)2NX (X = SiMe3 und ½b Hg) hergestellt und charakterisiert werden. In einer Vielzahl von Versuchen, wie z. B. Oxydation bzw. Photolyse ließ sich zeigen, daß die SN-Bindung in (C6F5S)2NH unter Bildung von C6F5SSC6F5 gespalten wird. Es konnte nachgewiesen werden, daß (C6F5S)3N chemisch wenig reaktiv ist; in der Kristallstrukturanalyse besitzen die Moleküle annähernd Cs-Symmetrie. Massen- und 13C-NMR-Spektren für (C6F5S)nNH3-n werden erstmals aufgeführt.
    Notes: The crystal structure of (C6F5S)3N has been examined. The compounds (C6F5S)2NX, X = SiMe3 and ½ Hg have been prepared from (C6F5S)2NH and characterised. In a number of other reactions, such as oxidation and irradiation, the S—N bond in (C6F5S)2NH was readily fractured, forming the disulfide, (C6F5S)2. The compound (C6F5S)3N has been found to be unreactive. Details of the mass and 13C NMR spectra of (C6F5S)nNH3-n, n = 1, 2, 3 are reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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