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1992 (1)
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1981 (2)
1Author    Dieter Brodalla, Rüdiger Kniep, Dietrich MootzRequires cookie*
 Title    A New Form of A1(H2P0 4 )3 with Three-Dimensional Al-O-P Crosslinking  
 Abstract    3 [A1(H 2 P0 4) 3 ] has been prepared and characterized as a second modification of alu-minium tris(dihydrogenphosphate). Its crystal structure is a three-dimensional Al-O-P network of AlOß octahedra, linked by common vertices through 0 2 P(0H) 2 tetrahedra with six further octahedra. Each P-OH group is a proton donor as well as a proton acceptor of 0-H---0 hydrogen bonds arranged in angular chains of alternating polarity in macroscopic domains. 
  Reference    Z. Naturforsch. 36b, 907—909 (1981); eingegangen am 18. Mai 1981 
  Published    1981 
  Keywords    Acid Aluminium Phosphates, Crystal Structure, Polymorphism 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0907.pdf 
 Identifier    ZNB-1981-36b-0907 
 Volume    36 
2Author    Rüdiger Kniep, Lutz Körte, Dietrich MootzRequires cookie*
 Title    Kristallstruktur der stabilen Modifikation von SeQi Crystal Structure of the Stable Modification of SeCU  
 Abstract    Single crystals of the stable modification of selenium tetrachloride (a-SeCU) were grown by sublimation, and the crystal structure was determined. As that of metastable ß-SeCU it contains tetrameric cubane-like molecules Se4Cli6, but with different point symmetry and in positions which correspond to those of the atoms of the tungsten structure type. 
  Reference    Z. Naturforsch. 36b, 1660—1662 (1981); eingegangen am 7. August 1981 
  Published    1981 
  Keywords    Selenium(IV) Chloride, Crystal Structure, Polymorphism 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1660_n.pdf 
 Identifier    ZNB-1981-36b-1660_n 
 Volume    36 
3Author    Rüdiger Kniep, Heinz Jürgen Beister, Dieter WaldRequires cookie*
 Title    Polymorphie von Tellur(IV)-iodid Polymorphism of Tellurium(IV) Iodide  
 Abstract    Idiomorphous crystals of five different polymorphic modifications (a—e) of Tel 4 are simultane-ously grown from solutions of Tel 4 and concentrated HI in methanol by evaporating the solvent at room temperature. (5-TeI 4 is the only stable phase at normal conditions. Phase transformations of a-, ß-, y-and £-TeI 4 to the final stage (5-TeI 4 take place by heating and run through discrete intermediates. The observed graduations lead to a sequence y-, ß-, a-,_e-TeI 4 which indicates "increasing metastability". The crystal structures of a-TeI 4 (trigonal; P3ml; a = 4.228(2), c — 6.684(6) A, Z = 0.5; D v = 5.10 g/cm 3), /3-TeI 4 (orthorhombic; Pn2,m; a = 6.888(2), b = 14.539(3), c = 16.753(4) Ä, Z = 8; D r = 5.03 g/cm 3) and y-TeI 4 (monoclinic; P2,/c; a = 11.199(4), b = 13.599(4), c = 22.158(6) Ä,/3 = 98.10(3)°, Z = 16; D, = 5.05 g/cm 3) are related to the known crystal structure of d-TeI 4 . a-TeI 4 ("Teo.s^") is an isotype of the 2H-CdI : structure with random distribution of Te over the Cd-positions. The crystal structures of ß-, y-and d-TeI 4 contain discrete tetrameric molecules "(TeI 4) 2 (Tel3 + I _)2" which are generated by ordered distributions of Te over 1/4 of the octahedral holes of a 2H-(ß) and a 4H-sequence (y, d) of the nearly close packed iodine layers. A nearly cubic close packing of Iodine atoms is observed in the crystal structure of £-TeI 4 (tetragonal; 14,/amd; a = 16.875(6), c -11.829(5) Ä, Z = 16; D v = 5.01 g/cm 3). The ordered distribution of Te in 1/4 of the octahedral holes leads to tetrameric molecules "(Tel 3 + I~) 4 " in a cubanelike arrangement which, thus far, has been observed only in the crystal structures of TeCl 4 and TeBr 4 . The Madelung Parts of Lattice Energies, MAPLE, of ß-, y-, d-and £-TeI 4 are calculated. 
  Reference    Z. Naturforsch. 43b, 966—980 (1988); eingegangen am 11. April 1988 
  Published    1988 
  Keywords    Polymorphism, Crystal Structures, Binary Compounds, Tellurium(IV) Iodide 
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 TEI-XML for    default:Reihe_B/43/ZNB-1988-43b-0966.pdf 
 Identifier    ZNB-1988-43b-0966 
 Volume    43 
4Author    Kerstin Müller3, AntonM. Heynsb, Klaus-Jürgen Range3, M. Anfred ZabelaRequires cookie*
 Title    The Polymorphism of Alkali Metal Formates, Part 3 A Raman Spectroscopic, X-Ray and Thermoanalytical Study of the Polymorphism of Lithium Formate  
 Abstract    The crystal structure o f anhydrous lithium formate, published recently by Kansikas and Hermansson, is in fact that o f a quenchable high-temperature m odification (L iH C O O -I). The low-temperature modification L iH C O O -II can be obtained by thermal dehydration o f the monohydrate, LiHCOO-H20 , or by drying it over P4O 10. L iH C O O -II persists up to 228 C, at which temperature it transforms to L iH C O O -I, which in turn is stable up to its melting point at 272 °C. L iH C O O -I is also the m odification which crystallizes when a melt o f lithium formate is cooled down, in spite o f the fact that solidification occurs only at 165 "C, i.e. at a temperature well within the stability region o f L iH C O O -II. The Raman spectra o f the differ­ ent forms o f lithium formate are discussed in some detail. 
  Reference    Z. Naturforsch. 47b, 238 (1992); received June 10 1991 
  Published    1992 
  Keywords    Lithium Formate, Polymorphism, Raman Spectra, Crystal Structure 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-0238.pdf 
 Identifier    ZNB-1992-47b-0238 
 Volume    47 
5Author    Hans Sohr, Günter Hanschmann, Hermann UtschikRequires cookie*
 Title    Thermoanalytische, IR-spektroskopische und quantenchemische Untersuchungen an Kristallmodifikationen des Trichlorphons Thermo-analytical, IR-spectroscopical and Quantum-chemical Investigations on Crystal Modifications of Trichlorphone  
 Abstract    Several modifications of trichlorphone can be prepared by recrystallizing the raw substance from various solvents under special conditions. One of these modifications is obviously an optical isomer. The different thermo-analytical behavior of the modifications is probably due to the relative content of distinct dimer species. This interpretation is supported by quantum-chemical calculations and by analysis of infrared spectra. Die phosphor-organische Verbindung 2.2.2-Tri-chlor-1 -hydroxyethyl-dimethyl-phosphonat (Tri-chlorphon, Metrifonat) ist ein seit etwa 30 Jahren bekanntes Insektizid [1], das auch als Arzneimittel für die Behandlung von Schistosomiasis eingesetzt wird [2]. Diese im folgenden als Trichlorphon be-zeichnete Substanz hat nach Schräder [3] einen Schmelzpunkt von 356-357 K. In den meisten Fäl-len hegen jedoch die von verschiedenen Autoren angegebenen Schmelzpunkte um 348-351 K. Bei der Reinigung von Trichlorphonproben durch Umkristallisieren stellten wir fest, daß man je nach den gewählten Bedingungen mehrere Kristallfor-men erhält, deren Schmelzpunkte zwischen 343 und 383 K variieren. Über die Erscheinung der Polymorphie beim Tri-chlorphon sind uns aus der Literatur keine Hinweise bekannt. Das Ziel unserer Untersuchungen war es deshalb, mit Hilfe strukturanalytischer Methoden eine Erklärung für die beobachteten Schmelzpunkts-differenzen zu finden. Von den bisher publizierten physikochemischen Eigenschaften der Substanz sind neben den zahl-reichen Schmelzpunkten hauptsächlich die optische Aktivität und die Bimolekularität als Ausgangs-punkt für eine Strukturanalyse von Bedeutung. Brienne und Jacques [4] gelang die präparative Dar-stellung einer optisch aktiven Form (Drehung [a] 
  Reference    Z. Naturforsch. 38b, 819—824 (1983); eingegangen am 29. November 1982/11. März 1983 
  Published    1983 
  Keywords    Differential Thermal Analysis, IR Spectra, Quantum Chemistry, Polymorphism, Trichlorphone 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0819.pdf 
 Identifier    ZNB-1983-38b-0819 
 Volume    38