Poly[diaqua(μ4-2,5-dicarboxybenzene-1,4-dicarboxylato-κ4 O 1:O 2:O 4:O 5)(μ2-2,5-dicarboxybenzene-1,4-dicarboxylato-κ2 O 1:O 4)bis(1,10-phenanthroline-κ2 N,N′)dimanganese(II)]

In the title compound, [Mn2(C10H4O8)2(C12H8N2)2(H2O)2]n, the Mn2+ ion has a slightly distorted octahedral N2O4 coordination geometry being coordinated by one aqua O atom, two N atoms of the chelating 1,10-phenanthroline ligand and three carboxyl O atoms from three 2,5-dicarboxybenzene-1,4-dicarboxylate (H2btec2−) ligands. The H2btec2− anion exhibits two different coordination modes, viz. μ2 and μ4. Both of the H2btec2− anions are located on special positions (inversion centers). The μ4-anion bridges adjacent MnII atoms, forming a chain along the a axis. Adjacent chains are further bridged by μ2-anions, resulting in a two-dimensional layered polymer parallel to (011). In the crystal, extensive carboxy–carboxylate O—H⋯O and water–carboxylate O—H⋯O interactions lead to the formation of a three-dimensional supramolecular network.

The title compound is isomorphic with previously reported cobalt(II) and zinc(II) analogs (Hu et al., 2004;Yu et al., 2007). The X-ray diffraction study indicates that the Mn II centers exhibit a slightly distorted octahedral MnN 2 O 4 coordination environment. Atom Mn1 is coordinated by one aqua O atom (O1W), two N atoms (N1 and N2) from a bridging 1,10-phenanthroline ligand and three carboxyl O atoms (O1, O7 and O5D) from three H 2 btec 2anions. The N1, N2, O1W and O7 atoms occupy the equatorial sites, while O1 and O5D occupy the axial positions ( Fig. 1 and Table 1).  (Fig. 2). The adjacent one-dimensional chains are further crosslinked by bridging µ 2 -H 2 btec 2anions, leading to a two-dimensional layered polymer (Fig. 3). Intermolecular O8-H8···O1 hydrogen bond and π-π interaction between the parallel phenantroline and µ 2 -H 2 btec 2ligands help to further stabilize the layered structure ( Fig.3 and Table 2). In the crystal structure, the two-dimensional polymeric layers are linked by carboxylic acid O-H···O carboxyl and water O-H···O carboxyl hydrogen bonds to form a three-dimensional supramolecular network structure (Fig.4).

Refinement
All non-hydrogen atoms were refined anisotropically. The H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.93 Å, O-H = 0.82 Å, U iso (H) = 1.2U eq (C) and U iso (H) = 1.5U eq (O). The H atoms of the water molecules were located in difference Fourier maps and freely refined.

Figure 1
The asymmetric unit of the title compound (displacement ellipsoids drawn at the 35% probability level). Unlabeled atoms are related to the labelled atoms by symmetry operators (symmetry codes:

Figure 2
The one-dimensional chain structure of the title compound. Dashed lines indicate hydrogen bonds. All C atoms of the phenantroline and µ 2 -H 2 btec ligands have been omitted for clarity (symmetry codes: i = 1 + x, y, z; ii = -x, -y, 2 -z).  The two-dimensional layer structure of the title compound viewed along the a axis. All H atoms have been omitted for clarity.

Figure 4
Hydrogen-bonding interactions between adjacent layers of the title compound. Dashed lines indicate hydrogen bonds.  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 R-factors(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.