Catenated polymeric molecular patterns in structures of two calcium(II) complexes with pyridine-2,3-dicarboxylate (quinolinic) and water ligands

Author： Starosta Wojciech Leciejewicz Janusz

Publisher： Taylor & Francis Ltd

ISSN： 0095-8972

Source： Journal of Coordination Chemistry, Vol.62, Iss.8, 2009-01, pp. : 1240-1248

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Abstract

The structure of triclinic catena-tetraquo(μ-pyridine-2,3-dicarboxylato-N,O; O')calcium(II) is composed of two symmetry independent Ca(II) ions and two independent ligand molecules. Each Ca(II) is coordinated by a N,O-bonding moiety of a ligand, four water oxygens, and a carboxylate oxygen donated by an adjacent bridging ligand. The resulting molecular ribbons are propagating in the [010] crystal direction. Both Ca(II) ions are eight coordinate forming a capped pentagonal bipyramidal with strongly distorted pentagonal equatorial planes. Hydrogen bonds between carboxylate oxygens and coordinated waters are responsible for the stability of the structure. The orthorhombic structure of catena-trisaquo[(μ-2, 3-dicarboxypyridin-1-ium-O,O'; O'') (H pyridine-2,3-dicarboxylato-N,O)]calcium(II) is composed of molecular ribbons in which the bridging of Ca(II) ions occurs through a ligand using one bidentate carboxylate. The other carboxylate of this ligand donates only one O atom to Ca(II), the second remaining inactive. A proton is attached to the hetero-nitrogen. Each Ca(II) is also chelated by a N,O-bonding moiety of a second ligand, which does not bridge and its second carboxylate remains protonated. Three water oxygen atoms complete the coordination around the Ca(II) ion to eight. The resulting coordination polyhedron is a capped pentagonal bipyramid with a strongly distorted equatorial plane. Hydrogen bonds in which coordinated waters act as donors are responsible for the stability of the structure.