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'Molecular motion' in keywords Facet   Publication Year 1995  [X]
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1Author    Barbara Szafrańska, Zdzisław PająkRequires cookie*
 Abstract    o le c u la r M o tio n in S o lid T e tr a e th y l-a n d T e tra p ro p y la m m o n iu m T e tr a f lu o r o b o r a te s Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetraethyl-and tetrapropylammonium tetrafluoroborates have been measured over a wide range of temperatures. Solid-solid phase transitions were found for both compounds and confirmed by DSC. Methyl group C3 reorientation followed by more complex cation motions was evidenced in the low temperature phases. Overall cation reorientation characterises the high temperature phases of both compounds. Isotropic anion reorientation was found in both salts in both phases. 
  Reference    Z. Naturforsch. 50a, 584—588 (1995); received August 15 1994 
  Published    1995 
  Keywords    NMR, Molecular motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0584.pdf 
 Identifier    ZNA-1995-50a-0584 
 Volume    50 
2Author    M. Grottel3, A. Kozakb, Z. PająkRequires cookie*
 Title    l H a n  
 Abstract    d 19F N M R S tu d y o f C a tio n a n d A n io n M o tio n s in G u a n id in iu m F lu o r o a n tim o n a te s Proton and fluorine NMR linewidths, second moments, and spin-lattice relaxation times of polycrystalline [C(NH2)3]2SbF5 and C(NH2)3SbF6 were studied in a wide temperature range. For the pentafluoroantimonate, C3-reorientation of the guanidinium cation and C4-reorientation of the SbF5 anion were revealed and their activation parameters determined. The dynamical inequivalence of the two guanidinium cations was evidenced. For the hexafluoroantimonate, two solid-solid phase transitions were found. In the low temperature phase the guanidinium cation undergoes C3 reorien­ tation while the SbF6 anion reorients isotropically. The respective activation parameters were derived. At high temperatures new ionic plastic phases were evidenced. 
  Reference    Z. Naturforsch. 50a, 742—748 (1995); received March 2 1995 
  Published    1995 
  Keywords    NMR, Molecular Motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0742.pdf 
 Identifier    ZNA-1995-50a-0742 
 Volume    50