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  • 1990-1994  (2)
  • 1994  (2)
  • Chemistry  (2)
  • IR  (1)
  • NMR  (1)
  • AZT
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  • 1990-1994  (2)
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  • 1
    ISSN: 0044-2313
    Keywords: Cyclosilazanes ; Boryl-bridged Rings ; Crystal Structure ; Pyrolises ; SiC/BN Composites ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Boryl-coupled Cyclotri- and -tetrasilazanes and four-membered Cycloborasilazanes - Thermal Decomposition to SiC and BNDilithiated octamethylcyclotetrasilazane reacts with a difluoroboryl substituted cyclotrisilazane to give the BF coupled 6-8-6-membered cyclosilazane 1, with Me2SiHCl structural isomeric cyclotetra- and cyclotrisilazanes of the type I and II, and with Me3SiCl structural isomeric cyclodisilazanes of the type III and IV are formed. The dilithium derivatives of the cyclosilazanes I and II as well as III and IV react with BF3 and a BF2-substituted cyclotrisilazane to give four-membered cyclo-borasilazanes which are coupled with a cyclodisilazane via a SiMe2-group (2-4). The six-membered cycloborasilazane 5 is a byproduct in the reaction with BF3. The reaction mechanisms are discussed. The pyrolysis with formation of SiC and BN and a crystal structure analysis were carried out with 1.
    Notes: Dilithiiertes Octamethylcyclotetrasilazan reagiert mit einem Difluorboryl-substituierten Cyclotrisilazan zum BF-gekoppelten 6-8-6-gliedrigen Cyclosilazan 1, mit Me2SiHCl zu strukturisomeren Cyclotetra- und Cyclotrisilazanen des Typs I und II und mit Me3SiCl zu strukturisomeren Cyclodisilazanen des Typs III und IV. Die Dilithiumderivate der Cyclosilazane I und II bzw. III und IV reagieren mit BF3 und einem BF2-substituierten Cyclotrisilazan zu viergliedrigen Cycloborasilazanen, die über eine SiMe2-Gruppe mit einem Cyclodisilazan verbunden sind (2-4). In der Reaktion mit BF3 wird als Nebenprodukt das sechsgliedrige Cycloborasilazan 5 isoliert. Die Reaktionsmechanismen werden diskutiert. 1 wird pyrolytisch zu SiC und BN zersetzt. Die Kristallstruktur von 1 wird vorgestellt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1357-1363 
    ISSN: 0044-2313
    Keywords: (Me2SiNCN)4 ; Me3SiNCNSiMe3 ; X-Ray ; NMR ; IR ; Raman ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal and Molecular Structures of (Me2SiNCN)4 (1) and Me3SiNCNSiMe3 (2)Synthesis, spectroscopic characterization (NMR, IR, Raman and MS) and crystal structure of the novel compound 1 are described. The molecules form almost planar 16 membered rings with four SiMe2-groups connected to four NCN groups. The corresponding compound 2 exhibits a phase transition from the HT phase 2a to the LT phase 2b at 131 K. Consecutive X-ray structure determinations of the molecular structures of both modifications were performed on a crystal, grown in situ on the diffractometer at 231 K.
    Notes: Für die neuartige Verbindung 1 werden Synthese, spektroskopische Charakterisierung (NMR, IR, Raman und MS) und die Kristallstruktur beschrieben. Das Molekül besteht aus einem nahezu planaren 16gliedrigen Ring, in dem vier SiMe2-Gruppen mit vier NCN-Gruppen verknüpft sind. Die Vergleichsverbindung 2 zeigt eine Phasenumwandlung von der HT-Phase 2a in die TT-Phase 2b bei 131 K. Die Molekülstrukturen beider Modifikationen wurden nacheinander durch Röntgenstrukturanalyse an einem in situ bei 231 K auf dem Diffraktometer gezüchteten Kristall bestimmt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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