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'Hydrogen bonding' in keywords Facet   Publication Year 1990  [X]
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1Author    Haruo Niki, Ryokan Igei, Takuya Higa, Masao Hashimoto, Takahiro IsonoRequires cookie*
 Title    Lattice Imperfections and Relaxation of Cl NQR in Chloral Iso-Butylhemiacetal  
 Abstract    The temperature dependence of the S/N ratios of three 35 C1 NQR lines (v l5 v 2 , v 3) in chloral iso-butylhemiacetal shows interesting features in the range 77-300 K. 35 C1 T y indicates that above 220 K reorientation of CC1 3 is excited, and this results in a gradual decrease in S/N. The activation energy calculated from 35 C1 NQR T l results is 30 kJ mol -1 for v x and v 2 but 25 kJ mol -1 for v 3 . The difference seems to be attributable to the motion of H in the OH group. A minimum of 35 C1 NQR T 2 is found around 180 K but 35 C1 T\ shows no anomaly. 35 C1 T 2 determines the S/N ratios in the range between 130-220 K. The line broadening below 130 K is attributable to an inhomo-geneity of the electric field gradient at resonant nuclei produced by lattice defects. 
  Reference    Z. Naturforsch. 45a, 481—484 (1990); received August 26 1989 
  Published    1990 
  Keywords    NQR, Lattice imperfections, Magnetic relaxation, Hydrogen bonding 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0481.pdf 
 Identifier    ZNA-1990-45a-0481 
 Volume    45 
2Author    Christian Robl, Stephanie HentschelRequires cookie*
 Title    Zur Kenntnis von Be[C2(C O O )2] * 4 H20 - Ein durch starke Wasserstoffbrückenbindungen stabilisiertes anorganisches Derivat der Acetylendicarbonsäure On Be[C2(COO)2]-4 H 20 -An Inorganic Derivative of Acetylenedicarboxylic Acid Stabilized by Strong Hydrogen Bonding  
 Abstract    Colorless orthorhombic single crystals o f Be[C2(COO)2] • 4 H 20 were grown in aqueous silica gel. Space group Cmcm, a = 1004.7(1), b = 675.0(1), c = 1262.4(2) pm, Rg = 0.0264. The crys­ tal structure consists o f Be(H20)^+ tetrahedra and planar [C2(COO)2]2' anions linked together by strong asymmetric hydrogen bonds. A layer-like arrangement extending parallel (010) made up by [C2(COO)2]2~ anions and hydrogen bound water m olecules o f the Be(H20)^ + tetra­ hedra is the primary structural feature o f Be[C,(COO)2] -4 H 20 . These layers are stacked and interlinked by coordinative bonds between Be^+ and H 20 to yield a rigid three-dimensional framework. Thermal decom position com m ences with endotherm ic loss o f water o f crystallisa­ tion at 160 °C followed by several steps o f exothermic degradation yielding finally a soot-like am orphous residue. 
  Reference    Z. Naturforsch. 45b, 1499—1502 (1990); eingegangen am 3. Mai 1990 
  Published    1990 
  Keywords    Beryllium Acetylenedicarboxylate, X -R ay Structure, Thermal Analysis, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/45/ZNB-1990-45b-1499.pdf 
 Identifier    ZNB-1990-45b-1499 
 Volume    45