Received 28 January 2013
The title compound, [Ba(C12H6O4)(H2O)2]n, is represented by a layer-like structure built of BaO8 polyhedra. The asymmetric unit contains a Ba2+ ion, half a coordinating water molecule and half a 4-bridging naphthalene-1,8-dicarboxylate (1,8-nap) ligand, the whole structure being generated by twofold rotational symmetry. The carboxylate groups of the 1,8-nap ligands act as bridges linking four Ba2+ ions, while each Ba2+ ion is eight-coordinated by O atoms from four 1,8-nap ligands and two coordinating water molecules. In the crystal, there are O-HO hydrogen bonds involving the water molecules and carboxylate O atoms in the BaO8 polyhedra. Each BaO8 polyhedron is connected via corner-sharing water O atoms or edge-sharing ligand O atoms, forming a sheet parallel to the bc plane. These sheets stack along the a-axis direction and are connected via van der Waals forces only. The naphthalene groups protrude above and below the layers of the BaO8 polyhedra and there are voids of ca 208 Å3 bounded by these groups. No residual electron density was found in this region. The crystal studied was twinned by pseudo-merohedry, with a refined twin component ratio of 0.5261 (1):0.4739 (1).
Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2556 ).
The authors acknowledge the Doctoral Foundation of Henan Polytechnic University (B2010-92, 648483).
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