catena-Poly[[[diaqua(1,10-phenanthroline-κ2 N,N′)cobalt(II)]-μ-1H-benzimidazole-5,6-dicarboxylato-κ2 N 3:O 6] sesquihydrate}

In the title compound, {[Co(C9H4N2O4)(C12H8N2)(H2O)2]·1.5H2O}n, the CoII atom is hexacoordinated by one N atom and one O atom from two symmetry-related 1H-benzimidazole-5,6-dicarboxylate ligands, two N atoms from one 1,10-phenanthroline ligand (phen) and two water molecules. The dihedral angle between the 1H-benzimidazole-5,6-dicarboxylate and 1,10-phenanthroline ligands is 74.41 (4)°. The crystal packing is governed by intermolecular O—H⋯O and N—H⋯O hydrogen-bonding interactions. All water (coordinating and lattice) molecules take part in the hydrogen-bonding interactions. In addition, there are π–π stacking interactions between inversion-related phen ligands, the shortest centroid–centroid distance being 3.7536 (16) Å. One of the two lattice water molecules shows half-occupancy.

As illustrated in Fig. 1 water and solvent water molecules lead to a two-dimensional layer (Fig. 2). The layers are further self-assembled into a three-dimensional supramolecular network by intermolecular N-H···O hydrogen bonds between the imidazole units and carboxylate groups (Table 1). In the crystal structure, π-π stacking interactions between inversion-related phen ligands are also observed with a shortest centroid-centroid distance of 3.7536 (16) Å [between (N4/C16/C18/C19/C20/C21) and
The crystals obtained were washed with water and dryed in air.

Refinement
Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C-H = 0.93 Å, N-H = 0.86 Å, and U iso (H) = 1.2U eq (C,N). The water H-atoms were located in a difference Fourier map, and were refined with distance restraint of O-H = 0.85 (2) Å and U iso (H) = 1.5U eq (O).

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level [H-atoms are shown as spheres of arbitrary size; symmetry code: (i) = x+2, y-0.5, -z+1.5].
supplementary materials

Figure 2
A view of the two-dimensional layer constructed by O-H···O and N-H···O hydrogen bonding interactions. 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 > 2sigma(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.