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1Author    Hiroyuki Ishida, Setsuo Kashino, Ryuichi IkedaRequires cookie*
 Title    Crystal Structure of Trimethylammonium Tetrafluoroborate in Three Solid Phases  
 Abstract    The crystal structure of (CH 3) 3 NHBF 4 was studied in three solid phases by X-ray diffraction techniques. The structures of the ionic plastic phase (Phase I) stable above 453 K and Phase II between 384 and 453 K are CsCl-type cubic (a = 5.772(4) Ä) and tetragonal (a = 9.815(5) and c = 6.895(5) A), respectively. The room temperature phase (Phase III) forms a monoclinic lattice (space group P2,/m, a = 5.7017(8), b = 8.5724(9), c = 7.444(1) Ä, and ß = 102.76(1)°). BF 4 ~ ions in this phase were shown to be disordered in four orientations. 
  Reference    Z. Naturforsch. 55a, 765—768 (2000); received June 28 2000 
  Published    2000 
  Keywords    Crystal Structure, X-ray Diffraction, Ionic Plastic Phase, Disorder 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0765.pdf 
 Identifier    ZNA-2000-55a-0765 
 Volume    55 
2Author    M. VeithRequires cookie*
 Title    Cyclische Diazastannylene, VIII [1] Die Kristall-und Molekülstruktur eines Iminostannylens: Sn3 (NC(CH3 )3 )4 H2 Cyclic Diazastannylenes, VIII [1] The Crystal and Molecular Structure of an Iminostannylene: Sn3(NC(CH3)3)4H2  
 Abstract    The crystal and molecular structure of the compound Sn3(NC(CH3)3)4H2 has been determined from X-ray data (R = 0.044). The crystals are cubic, space group Pa3, with cell dimension a — 1713.6(8) pm and Z = 8. The molecules, which have a seco-norcubane like Sn3N4 framework, are statistically disordered, thus forming closed packed pairs of molecules. The Sn3N4 cage deviates strongly from a cube, the bond angles at Sn approach-ing 80°, and at N 100°. The averaged Sn-N bond distance is 223(1) pm. 
  Reference    (Z. Naturforsch. 35b, 20—24 [1980]; eingegangen am 3. September/8. Oktober 1979) 
  Published    1980 
  Keywords    Iminostannylenes, X-ray, Crystal Structure, Molecular Structure, Disorder 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0020.pdf 
 Identifier    ZNB-1980-35b-0020 
 Volume    35 
3Author    HeinzW. Rotter, Gerhard ThieleRequires cookie*
 Title    Fehlordnung von Kationen und Kristallwasser bei kubischen Alkalitetrabromo-und -iodothallaten(III) Disorder of Cations and Water Molecules in Cubic Tetrabromo-and -iodothallates  
 Abstract    Tetrabromo-and -iodothallates(III) of the alkali cations crystallise from aqueous solutions as cubic hydrates MTlX4-nH20 (M = Li, Na, K, Rb, Cs, NH4; X — Br, I; n — 1-2). The tetraiodothallates retain their cubic structure on dehydratisation, while the tetrabromothallates undergo structural changes. The X-ray structure analyses of RbTlBr4 • H20, NH4TlBr4 • 2HoO and KTlBr4 • 2H20 (—50 °C) showed that these com-pounds consist of a three-dimensional framework of TlBr4 tetrahedra and MBrjo ikosahedra which reminds of zeolites. In cavities of this framework 2/3 of the alkali cations and the crystal water molecules are accommodated in a disordered manner. 
  Reference    Z. Naturforsch. 37b, 995—1004 (1982); eingegangen am 3. März 1982 
  Published    1982 
  Keywords    Thallium, Tetrabromothallate, Disorder, Tetraiodothallate, Crystal Structure 
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 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0995.pdf 
 Identifier    ZNB-1982-37b-0995 
 Volume    37 
4Author    Takahiro Ueda, Katsuyuki Shimizu, Hiroshi Ohki, Tsutomu OkudaRequires cookie*
 Title    C CP/MAS NMR Study of Motion and Local Structure of Phenethyl- ammonium Ion in [C 6 H 5 CH 2 CH 2 NH 3 ] 2 PbX 4 (X = Cl, Br, I)  
 Abstract    Ionic motion and local structure of phenethylammonium ion (C 6 H 5 CH-,CH 2 NH 3 +) in a series of phenethylammonium lead(II) halides, [C 6 H 5 CH 2 CH 2 NH 3 ] 2 PbX 4 (X = Cl, Br, I) were studied by means of 13 C cross polarization/magic angle sample spinning (CP/MAS) NMR technique. Among the three salts, remarkable differences in the spectra were observed in the signals corresponding to the phenyl carbons. The peaks from C2, C3, C5, and C6 in the phenyl group were split into three for the chloride and into two for the bromide, although in the iodide those were observed as a single peak. Coalescence of those peaks, as well as line broadening were observed on heating. This indicated that peak split brings about disorder of the orientation in the phenyl group around the C1-C4 axis, suggesting to have three and two orientations for the chloride and the bromide, respectively. Above room temperature the phenyl group undergoes chemical exchange among these orientations, and at higher temperature, reorientation with a large amplitude takes place around its axis. The apparent activation energies of the reorientation of the phenyl group for the chloride and bromide were estimated from the temperature dependence of the linewidth of the resonance peaks to be about 24 kJ mol -1 , 25 kJ mol -1 , respectively, which is similar to in the iodide (25.0 kJ mol -1). Ab initio molecular orbital energy calculation was carried out to evaluate the potential barrier of the internal rotation of the phenyl group in a free phenethylammonium ion. The intramolecular interaction was evaluated to be 13.9 kJ mol -1 from the calculation, and the intermolecular interaction results to be 10 kJmol -1 . 
  Reference    Z. Naturforsch. 53a, 983—988 (1998); received April 30 1998 
  Published    1998 
  Keywords    13 C CP/MAS NMR, Layered compound, Disorder, Reorientation, Activation energy 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0983.pdf 
 Identifier    ZNA-1998-53a-0983 
 Volume    53