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  • 1
    ISSN: 0009-2940
    Keywords: Crystal dynamics ; Fluctional solids ; N-Base - organoboron adducts ; Phase transformations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Röntgenstrukturanalyse und molekulare Dynamik von Festkörper-Phasenumwandlungen der N-Base-Addukte des Bis(1,5-cyclooctandiyl)diboroxansVon zwei Lewis-Base-Addukten des Bis(1,5-cyclooctandiyl)diboroxans (1) (mit Pyridin: P-1; Quinuclidin: Q-1) mit Fest-„Fest“-Phasenumwandlungen bei 127 bzw. 88°C wurden Röntgenstrahlbeugungs-Strukturen bei -145 bzw. -163°C ermittelt. Von Q-1 wurde zusätzlich die Struktur bei Raumtemperatur und bei +50°C bestimmt. P-1 und Q-1 sind im Gitter als Paare geordnet und zeigen umfangreiche isotherme und temperaturabhängige Dynamik in kristalliner Phase. Der Übergang in die neue, „fluktuierende Festkörper“-Phase wird unter Einbeziehung der Gitteranordnung, der beobachteten Intragitter-Translative und der vibrativen Bewegungsvorgänge diskutiert.
    Notes: The structures of the two adducts P-1 and Q-1 of bis(1,5-cyclooctanediyl)diboroxane (1) with pyridine (P) and quinuclidine (Q), which show solid-„solid“ phase transformations at about 127 and 88°C, respectively, have been determined by X-ray diffraction at -145 and -163°C, respectively. The structure of Q-1 has also been determined at room temperature and at +50°C. Both P-1 and Q-1 are packed in head-to-tail pairs and show extensive isothermal as well as temperature-dependent dynamics in the crystalline phase. The onset of transformations into the new „fluctional solid“ phase is discussed in terms of these lattice packings and the observed translational and vibrational dynamics.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 309-313 
    ISSN: 0009-2940
    Keywords: Bis(1,5-cyclooctanediylboryl) oxide, N-base adducts of, solid state NMR of ; Fluctional crystals ; Crystal dynamics ; Phase transformations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The adducts of bis(1,5-cyclooctanediylboryl) oxide (1) with quinuclidine (2a) and with pyridine (2b) show an unusually large premelting endothermic phase transition. 2a has been investigated by 11B-NMR spectroscopy in the solid state and at various temperatures in its mesophase. The significant differences in the lattice packings of the molecules of the thermally stable adducts of 1 with 4-methyl-, 3-bromo-, and 4-(dimethylamino)pyridine (2c - e; X-ray structural analysis) from those of 2a and 2b suggests that it is the unique molecular arrangement in the respective lattices of the latter two adducts which allows a smooth transition to a two-dimensionally ordered mesophase. This is stabilized by intermolecular fluctuation of the N-base molecules between the boron atoms of the neighbouring molecules of 1.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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