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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 29 (1999), S. 45-55 
    ISSN: 1572-8854
    Schlagwort(e): Melaminium dinitramide and melaminium nitrate ; melaminium salts ; dinitramide salt ; hydrogen bonding ; X-ray structure ; energetic materials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Two energetic salts of the melaminium cation have been prepared and structurally characterized from room temperature X-ray single crystal diffraction data. Melaminium dinitramide (I), triclinic, P1¯, a = 6.6861(11), b = 6.9638(16), c = 10.447(2) Å , α = 99.07(3), β = 98.30(3), γ = 108.50(3)°, V = 445.6(2) Å3, and Z = 2. Melaminium nitrate (II), monoclinic, P21/c, a = 3.5789(7), b = 20.466(4), c = 10.060(2) Å, β = 94.01(2)°, V = 735.0(3) Å3, and Z = 4. The crystal structures of both salts show distinct monoprotonated melaminium cations and dinitramide- or nitrate anions, respectively. Efficient packing in the solid state is achieved by extensive hydrogen bonding between two-dimensional zigzag ribbons of the melaminium cations and the respective anions resulting in high densities of the solid state structures of 1.74 (I) and 1.71 g/cm3 (II).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1572-8854
    Schlagwort(e): 2-phenylglycerol ; x-ray structure ; computational studies ; conformations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract 2-Phenylglycerol has been crystallized, structurally characterized, and its related conformations considered by ab initio calculations at the HF/6-31G* level. C9H12O3. $$ \frac{1}{2} $$ H2O, P21,a = 5.8786(1), b = 28.6605(7), c = 10.5553(3) Å, β = 90.187 (1)° at 100(1) K, Z = 8, R = 0.0424 for 5913 unique observed reflections. The asymmetric unit contains four molecules of the title compound and two molecules of water. The structures are characterized by extensive intermolecular hydrogen bonds. The packing is dominated by a hydrophilic hydrogen bonded layer with the hydrophobic phenyl rings forming a herringbone packed intermediate layer. Computational studies suggest that an increase in energy of about 13 kcal/mol can provide for significant conformational flexibility, including the traversal of an orientation that is appropriately aligned with the reaction trajectory needed for closure to the oxetane. Progression along this reaction coordinate, however, will probably require at least another 15 kcal/mol in the gas phase in order to bring the two SN2 species into a proximity which approaches that of the oxetane's C-O bond distance.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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