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'crystal and molecular structure' in keywords
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1997 (1)
1983 (2)
1Author    A. R. Ofial, S.-Q Dou, V. G. Krishnan, H. Paulus, H. Fuess, Al WeissRequires cookie*
 Title    X-Ray and 35 C1 NQR Studies on the Trichloroacetyl Group in Covalent and Ionic Compounds of L-Valine and DL-Valine  
 Abstract    The crystal structures and 35 C1 NQR of trichloroacetyl-DL-valine (1), trichloroacetyl-L-valine (2), as well as the salts of trichloroacetic acid with DL-valine (3) and L-valine (4) have been investigated. Crystal data are for (1): Monoclinic, C2/c, a= 15.835(4) Ä, b= 10.481 (3) Ä, c = 14.046(4) A, /? = 103.28(1), Z = 8; (2): Orthorhombic, P2 1 2 1 2 1 , a = 12.117(3) Ä, 6=10.896(3) Ä, c= 8.718(2) Ä, Z = 4; (3): Triclinic, PI, a= 17.269(3) Ä, 6 = 8.504(3) Ä, c = 10.427(4) A, a = 105.38(2), £ = 96.98(2), y = 96.24(2), Z = 2; (4): Monoclinic, P2 1? a = 10.378(4) A, 6 = 20.349(8) A, c= 11.890(5) A, B = 95.28(2), Z = 8. The onset of rotational motion within the trichloroacetyl groups bleaches out 35 C1 NQR lines between 115 K and 185 K for (l)-(4). While TCA-L-valine (1), TCA-DL-valine (2), and TCA*) • DL-valine (+) (3) do not show any phase transition in the temperature range 77 K to 295 K, TCA <_) • L-valine (+) (4) shows more than one phase transition above 77 K before the three NQR signals bleach out at 164 K. 
  Reference    Z. Naturforsch. 52a, 249—258 (1997); received August 30 1996 
  Published    1997 
  Keywords    35 C1 NQR study, trichloroacetyl, valine, crystal and molecular structure 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0249.pdf 
 Identifier    ZNA-1997-52a-0249 
 Volume    52 
2Author    Reinhold Tacke, Hartwig Lange, WilliamS. Sheldrick, Günter Lambrecht, Ulrich Moser, Ernst MutschierRequires cookie*
 Title    Sila-Pharmaka, 31. Mitt. [1] Synthese, Struktur und pharmakologische Eigenschaften von Diphenyl(2-piperidinoethoxymethyl)silanol und seinem Kohlenstoff-Analogon Sila-Pharmaca, 31 th Communication [1J Synthesis, Structure, and Pharmacological Properties of Diphenyl(2-piperidinoethoxymethyl)silanol and its Carbon Analogue  
 Abstract    In the course of systematic investigations on sila-substituted parasympatholytics the diphenyl(2-aminoethoxymethyl)silanols 3b and 4b (and its carbon analogue 4a) were synthesized and characterized by their physical and chemical properties. In the solid state 4a and 4b form strong 0-H---N hydrogen bonds, which are intramolecular (4a) and intermolecular (4b), respectively. 4 a and 4 b were found to be weak antimuscarinic agents (4b >4a) and strong papaverine-like spasmolytics (4a ^4b). 
  Reference    Z. Naturforsch. 38b, 738—746 (1983); eingegangen am 5. Januar 1983 
  Published    1983 
  Keywords    Sila-Substitution, Crystal and Molecular Structure, Antimuscarinic and Papaverine-Like Activity 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0738.pdf 
 Identifier    ZNB-1983-38b-0738 
 Volume    38 
3Author    Gerhard Klebe, JanW. Bats, Karl HensenRequires cookie*
 Title    Coordinative Interactions in Chelated Complexes of Silicon, Part HI Crystal and Molecular Structure of l-Trichlorosilyl-l,2,3,4-tetrahydro-l,10-phenanthroline  
 Abstract    The crystal structure of Ci2HiiN2SiCl3 (monoclinic, P2i/m, Z = 2, with a: 9.284(4), b: 7.226(2), c: 10.832(5) Ä, ß = 115.14(3)°) was refined to R(F) -0.035 from 1228 inde-pendent reflections. A trigonal bipyramidal, pentacoordinate silicon is observed. The chelated complex shows two different Si-N bonds, a coordinative bond (1.984(2) A) be-tween Si and N on the axial position and a Si-N single bond (1.737(3) A, equatorial plane), introduced by chemical reaction. The coordinative bond is 14.2% longer than the Si-N single bond. The lengthening of the coordinative bond in the present case is compared with distances in other extracoordinated silicon compounds. 
  Reference    Z. Naturforsch. 38b, 825—829 (1983); received March 23 1983 
  Published    1983 
  Keywords    Crystal and Molecular Structure, Chelated Pentacoordinated Silicon, Lewis Acid Base Interactions, Coordinative Bonding 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0825.pdf 
 Identifier    ZNB-1983-38b-0825 
 Volume    38