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  • 1980-1984  (2)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 11 (1981), S. 117-124 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of 2-aminophenol has been redetermined from automatic diffractometer data in order to locate the hydroxyl and amino hydrogens and confirm the nature of the intermolecular hydrogen bonding. Crystals are orthorhombic, space groupPbca, witha =19.751(6),b = 7.250(3), andc = 7.852(5) Å, and eight molecules per cell. The structure was solved by Multan and refined to a conventionalR value of 0.030. The molecular geometry compares well with previously reported structures of related species. The molecules are hydrogen bonded from OH to N to form chains parallel to theb axis, with these chains linked together to form sheets by NH to O hydrogen bonds essentially parallel toc. The NH - O hydrogen bonds are 0.33 Å longer than the OH - N ones, and an explanation for this is provided which incorporates newly computed values for atomic electronegativities. Pairs of molecules are mutually hydrogen bonded across inversion centers. There are large cavities between the sheets which could conceivably result in easy intercalation of small foreign molecules, much as in the clathrates formed by urea and β-quinol.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 13 (1983), S. 263-272 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of 3-ammonium-4-hydroxyphenylarsonic acid chloride dihydrate has been determined from single-crystal diffraction data. The compound crystallizes in the orthorhombic space groupPna 21 with four molecules in a unit cell of dimensionsa=17.712(7),b=13.468(4), andc=4.798(2) Å. The structure was solved by the Patterson method and refined to a finalR value of 2.1%. The average C-C phenyl distance is 1.393 Å, but two bonds are somewhat shorter than the others. This, coupled with the fact that the C-O and C-As bonds are shorter than normal, makes it appear as if there is a minor resonance contributor of a keto form. The C-N bond length of 1.443 Å is intermediate between values found in aminophenols and other ammoniumphenols. The H2AsO3 group is nearly tetrahedral, with the double-bonded oxygen rotated 9° out of the phenyl plane about the C-As bond. There is an extensive hydrogen-bonding system, involving every one of the OH and NH hydrogens, through the chloride and the waters of crystallization.
    Type of Medium: Electronic Resource
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