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'Hydrogen bonding' in keywords Facet   Publication Year 1988  [X]
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1988[X]
1Author    Christian RoblRequires cookie*
 Title    Erdalkaliquadratate, VI [1] SrC 4 0 4 -3H 2 0, Typ III Alkaline-earth Squarates, VI [1] SrC 4 0 4 -3H 2 0, Type III  
 Abstract    SrC 4 0 4 -3H 2 0, type III, was obtained in an aqueous silica gel besides crystals of SrC 4 0 4 • 3 H 2 0, type I. X-ray crystal structure analysis showed close relationship to BaC 4 0 4 -3H 2 0, but no iso-typism. Sr 2+ is coordinated by four water molecules and four oxygen atoms of the squarate dianion. The connection of Sr 2+ with C 4 0 4 2 leads to layers. The geometry of C 4 0 4 2 is typical for delocalized jr-systems. The O squarate atoms are not equally bound to Sr 2+ . One O squarate atom (0(4)) is bound to two Sr 2+ , two (O(l), 0(2)) are bound to one Sr 2+ , respectively, and the fourth O squaraIe atom (0(3)) shows no bonding contact to Sr 2+ . These differences are compensated for by inter-molecular hydrogen bonds which involve 0(3) three times, O(l) and 0(2) once each, but not 0(4). 
  Reference    (Z. Naturforsch. 43b, 99—103 [1988]; eingegangen am 21. September 1987) 
  Published    1988 
  Keywords    Strontium Squarate Type III, Preparation, Crystal Structure, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_B/43/ZNB-1988-43b-0099.pdf 
 Identifier    ZNB-1988-43b-0099 
 Volume    43 
2Author    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