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1Author    Requires cookie*
 Title    Röntgenographische Strukturuntersuchung von Cäsiumhexaoxo-tetrahydroxo-pentaborat-2-dimethylsulfoxid X-ray Study of the Structure of Cesiumhexaoxo-tetrahydroxo-pentaborate-2-dimethyl Sulfoxide  
 Abstract    The compound Cs[Bs0 6 (OH)4 ] • 2 DMSO was prepared by hydrolysis of tris(methoxy)-borane in organic solvents with small amounts of water in presence of cesium ierf-butylate and recrystallized in DMSO (dimethyl sulfoxide). Cs[Bs0 6 (0 H)4 ] • 2 DMSO crystallizes in the monoclinic space group P2i/a with a = 9.593(2), 6 = 19.179(4), c = 11.585(2) Ä, ß = 119.99(2)° and Z — 4. The crystal structure was determined by single-crystal diffracto­ meter data and refined to a conventional R value of 9.9%. The crystal structure consists of chains of pentaborate anions [Bs0 6 (OH)4 ]-linked by hydrogen bonds. The cesium cation and the DMSO molecules join the chains to sheets by coordination and hydrogen bonds respectively. 
  Reference    (Z. Naturforsch. 32b, 268—274 [1977]; eingegangen am 4. November/7. Dezember 1976) 
  Published    1977 
  Keywords    X-ray, Crystal Structure, Isopolyanions, Polyborates 
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 TEI-XML for    default:Reihe_B/32/ZNB-1977-32b-0268.pdf 
 Identifier    ZNB-1977-32b-0268 
 Volume    32 
2Author    Ralf Janda, Gert HellerRequires cookie*
 Title    Investigations of Solid Polyborates and their Aqueous Solutions by Raman Spectroscopy  
 Abstract    Raman spectra of solid H3B03, Na2[B405(0H)4] • 8 H20, K[B506(0H)4] • 2 H20 and Na[B(OH)4] were recorded between 300 and 1500 cm -1 as well as of borax in aqueous solutions as a function of concentration and pH. Because of better solubility in water, the Raman spectrum of ammonium tetraborate in aqueous solution was also recorded as a function of pH. For comparisons the Raman spectra of solid (NH4)2[B40s(0H)4] • 2 H20, /S-NH4[B506(0H)4] • 2 HsO, NH4[B506(0H)4] • 0,67 H20 and NH4[B506(0H)4] were con-sidered. In solution, all lines in the Raman spectra could be assigned and the degree of depolarization measured. The assigned Raman frequencies can be used for the identifica-tion of unknown B-0-lines and therefore of unknown borate or polyborate structures. 
  Reference    Z. Naturforsch. 34b, 585—590 (1979); eingegangen am 27. November 1978/23. Januar 1979 
  Published    1979 
  Keywords    Polyborates, Ammonium Borates, Sodium Borates, Raman Spectroscopy, Identification 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0585.pdf 
 Identifier    ZNB-1979-34b-0585 
 Volume    34 
3Author    Ralf Janda, Gert HellerRequires cookie*
 Title    1 B—NMR-spektroskopische Untersuchungen an wäßrigen Polyboratlösungen n B NMR Spectroscopic Studies on Aqueous Polyborate Solutions  
 Abstract    The U B nuclear magnetic resonance spectra of sodium, potassium and ammonium polyborates in aqueous solutions, -as a function of concentration and pH -, provide information of the hydrolysis equilibria. Two n B NMR lines are observed in aqueous solutions of Na[B506(0H)4], K[B506(0H)4] and NH4[B506(0H)4]. Only one n B NMR line is recorded in aqueous solutions of (NH4)2[B4Os(OH)4] and Na2[B4Os(OH)4]. The results of the U B NMR spectra are discussed and compared with the results obtained from Raman studies of aqueous polyborate solutions. 
  Reference    Z. Naturforsch. 34b, 1078—1083 (1979); eingegangen am 13. März/27. April 1979 
  Published    1979 
  Keywords    n B NMR, Borates, Polyborates, Hydrolysis, Equilibria 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1078.pdf 
 Identifier    ZNB-1979-34b-1078 
 Volume    34 
4Author    Ulrich Timper, Gert Heller, M. Ahm Ood, Shakibaie-M OghadamRequires cookie*
 Title    Sborgit und /?-Sborgit -eine zweite synthetische Modifikation von Na[B50 6(0 H )4] * 3 H 20 Sborgit and /?-Sborgit -a Second Synthetic M odification of Na[B50 6(0 H )4] * 3 H 20  
 Abstract    In crystallization experiments for silver borate hydrates from solutions o f borax, boric acid, and silver nitrate, a mixture o f sborgite and a second m odification -named by us "/?-sborgite" -have been found besides excess H 3B 0 3 and a microcrystalline silver borate. Both m odifica­ tions contain the same distorted pentaborate ion [B50 6(0 H)4]~. Both N a + ions in the asym­ metric unit are in special positions along the binary axis; one, N a (l), is octahedrally coordinat­ ed by four H20 molecules and two OH groups, the other one, N a(2), is tetrahedrally coordi­ nated by two H 20 molecules, two OH groups and -at longer distances -with two bridging oxygen atom s o f the pentaborate unit. The different angles -only a small rotation on the b-axis -o f the pentaborate anions between an identical matrix o f N a-cations give rise to the two different modifications. 
  Reference    Z. Naturforsch. 45b, 1155—1166 (1990); eingegangen am 7. Juni 1989/25. Januar 1990 
  Published    1990 
  Keywords    Sborgite, Polyborates, Sodium Pentaborate, M odification 
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 TEI-XML for    default:Reihe_B/45/ZNB-1990-45b-1155.pdf 
 Identifier    ZNB-1990-45b-1155 
 Volume    45 
5Author    Takao OiRequires cookie*
 Title    Ab initio Molecular Orbital Calculations of Reduced Partition Function Ratios of Polyboric Acids and Polyborate Anions  
 Abstract    Molecular orbital calculations at the HF/6-3 lG(d) level were carried out for polyboric acids and poly-borate anions up to a pentamer to estimate their "B -to-B isotopic reduced partition function ratios (RPFRs) and examine the additivity of logarithms of RPFRs. Approximate RPFR-values calculated by the use of the additivity agreed with exact RPFR-values within a margin of 1% error. This error was equivalent to a 5% error on ln(RPFR). The equilibrium constants of mono boron isotope exhange reac-tions between three-coordinate boron and four-coordinate boron ranged from 1.0203 to 1.0360 at 25 °C, indicating the importance of exact evaluation of RPFRs of polymers. 
  Reference    Z. Naturforsch. 55a, 623—628 (2000); received March 18 2000 
  Published    2000 
  Keywords    Ab initio Molecular Orbital Calculations, Polyborates, Reduced Partition Function Ratios, Boron Isotope Exchange, Isotope Fractionation 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0623.pdf 
 Identifier    ZNA-2000-55a-0623 
 Volume    55