Poly[tetraaqua(μ4-benzene-1,3,5-tricarboxylato)sodium(I)zinc(II)]

In the title compound, [NaZn(C9H3O6)(H2O)4]n, the ZnII atom is six-coordinated by four O atoms from two different benzene-1,3,5-tricarboxylate anions and two water O atoms in a distorted tetragonal-bipyramidal geometry and the NaI atom is five-coordinated by three O atoms from three different benzene-1,3,5-tricarboxylate anions and two water O atoms in a distorted trigonal-bipyramidal geometry. The benzene-1,3,5-tricarboxylate anion bridges two ZnII atoms and two NaI atoms, resulting in the formation of a two-dimensional layer structure. Intermolecular O—H⋯O hydrogen-bonding interactions generate a three-dimensional superamolecular structure.

In the title compound, [NaZn(C 9 H 3 O 6 )(H 2 O) 4 ] n , the Zn II atom is six-coordinated by four O atoms from two different benzene-1,3,5-tricarboxylate anions and two water O atoms in a distorted tetragonal-bipyramidal geometry and the Na I atom is five-coordinated by three O atoms from three different benzene-1,3,5-tricarboxylate anions and two water O atoms in a distorted trigonal-bipyramidal geometry. The benzene-1,3,5tricarboxylate anion bridges two Zn II atoms and two Na I atoms, resulting in the formation of a two-dimensional layer structure. Intermolecular O-HÁ Á ÁO hydrogen-bonding interactions generate a three-dimensional superamolecular structure.

Experimental
The mixture of of benzene-1,3,5-tricarboxylate acid (0.063 g, 0.3 mmol), NaOH (0.024 g, 0.25 mmol), Zn(Ac) 2 (0.066 g, 0.3 mmol), and 10 ml H 2 O was sealed in 18 ml Teflon-lined stainless steel container. The container was heated to 150 °C and held at that temperature for 72 h, then cooled to room temperature at a rate of 10 °C.h -1 . And then crystals of the title compound were isolated.

Refinement
C-bound H-atoms were geometrically positioned (C-H = 0.93 Å) and refined using a riding model, with U iso (H) = 1.2U eq (C). The H atoms of the water molecules were located in a difference map, and were refined with distance restraints of O-H = 0.85 Å. Fig. 1. ORTEP diagram of the coordination environments for Zn II atom and Na I atom in (I), showing 30% probability displacement ellipsoids, crystalline water molecules and the atomic numbering scheme [symmetry code: (i) 1-x, y, 1.5-z; (ii) x-0.5, 1.5-y, z-0.5; (iii) x, y-1, z]. H atoms have been omitted for clarity.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.