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1993 (1)
1988 (1)
1Author    Christian RoblRequires cookie*
 Title    Komplexe mit aromatischen Carbonsäuren, IV [1] Ca 2 [C 6 H 2 (COO) 4 ] * 6 H 2 0 -Eine neue Schichtstruktur Complexes with Aromatic Carboxylic Acids, IV [1] Ca 2 [C 6 H 2 (C00) 4 ]-6H 2 0 -A Novel Layer Structure  
 Abstract    Single crystals of Ca 2 [C 6 H 2 (COO) 4 ]-6H 2 0 were grown in aqueous silica gel. Ca :+ hasCN 6+2. The coordination polyhedron is formed by three water molecules and five oxygen atoms of carboxylate groups. Six oxygen atoms are closely bound (235,9—243,9 pm), the two remaining coordination partners are considerably more remote from Ca 2+ (268,2 and 273,8 pm). COO" groups chelate Ca :+ in an asymmetric manner, but the C —O bond lengths do not differ markedly (125,2—126,3 pm). The connection of Ca 2+ with [C,H 2 (COO) 4 ] 4_ leads to rigid layers. Adjacent layers are interlinked by hydrogen bonds. Those oxygen atoms which are weakly bound to Ca 2+ are favoured as proton acceptors in hydrogen bonds. The COO groups are tilted differently against the C 6 -ring plane. One is approximately coplanar, but the other is oriented almost perpen-dicularly. 
  Reference    Z. Naturforsch. 43b, 993—997 (1988); eingegangen am 11. April 1988 
  Published    1988 
  Keywords    Pyromellitate, Layer Structure, Preparation, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/43/ZNB-1988-43b-0993.pdf 
 Identifier    ZNB-1988-43b-0993 
 Volume    43 
2Author    Christian Robl, M. Ona FrostRequires cookie*
 Title    Na6[TeMo60 24l ' 22 H20 -A Layered Heteropoly Compound with the Chain-Like Polycation {N a3(H 20 ) n }^/,+  
 Abstract    Colourless triclinic single crystals of N a6[TeMo60 24] • 22 H-,0 were grown from aqueous so­ lution (space group P i, a = 1030.89(9), 6 = 1056.7(1), c = 1106.32(9) pm, a = 90.120(7), ß = 115.220(6), 7 = 105.195(7) , Z = 1, 295 K, 336 param eters, 3181 reflections, Rg = 0.0186). There are three crystallographically independent N a+ cations. Two of them are coordinated octahedrally by water molecules only. The third N a+ cation is bound to five H 20 and one oxy­ gen atom (0(4)) belonging to the Anderson-Evans type anion [TeMo60 24]6~. The sodium-cen­ tered coordination octahedra are linked by common edges exclusively formed by water mole­ cules to yield chain-like polycations {Na-,(H20) ,,} ^ + which are bound by the N a (l) -0 (4) con­ tact to the anions situated on crystallographic centers o f inversion forming a layer-like arrangement. Further connections "between the polycations and the [TeM o60 24]6" anions are established by hydrogen bonds involving all the oxygen atom s of the anion except 0(4) as al­ most equivalent proton acceptors regardless of their bonding mode to Te or Mo. 
  Reference    Z. Naturforsch. 48b, 404—408 (1993); received November 12 1992 
  Published    1993 
  Keywords    Hexamolybdotellurate, Layer Structure, Polycations, Crystal Structure Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/48/ZNB-1993-48b-0404.pdf 
 Identifier    ZNB-1993-48b-0404 
 Volume    48