trans-Diaquabis[5-carboxy-2-(3-pyridyl)-1H-imidazole-4-carboxylato-κ2 N 3,O 4]manganese(II)

In the title compound, [Mn(C10H6N3O4)2(H2O)2], synthesized by hydrothermal reaction, the MnII ion lies on an inversion centre and displays a distorted octahedral coordination geometry defined by the two imidazole N atoms and two carboxylate O atoms of the two trans-standing chelate ligands, and two O atoms of the water molecules. A two-dimensional supramolecular architecture is formed via N—H⋯O, O—H⋯N and O—H⋯O hydrogen-bonding interactions.

In the title compound, [Mn(C 10 H 6 N 3 O 4 ) 2 (H 2 O) 2 ], synthesized by hydrothermal reaction, the Mn II ion lies on an inversion centre and displays a distorted octahedral coordination geometry defined by the two imidazole N atoms and two carboxylate O atoms of the two trans-standing chelate ligands, and two O atoms of the water molecules. A two-dimensional supramolecular architecture is formed via N-HÁ Á ÁO, O-HÁ Á ÁN and O-HÁ Á ÁO hydrogen-bonding interactions.

trans-Diaquabis[5-carboxy-2-(3-pyridyl)-1H-imidazole-4-carboxylatoκ 2 N 3 ,O 4 ]manganese(II)
Li-Zhuang Chen S1. Comment N-Heterocyclic carboxylic acids, such as imidazole-4,5-dicarboxylic acid, are recognized as efficient N,O-donors, exhibiting diverse modes of coordination (Zhang et al., 2004;Xiao et al., 2004;Lu et al., 2006). In this work, we have chosen 2-Pyridin-3-yl-1H-imidazole-4,5-dicarboxylic acid as the building block to obtain the title compound, and we present its crystal structure here. Mn II ion lies on an inversion centre and displaying distorted octahedral coordination geometry defined by the two imidazole N atoms, two O toms of the carboxylate groups and two O atoms of the water molecules. The pyridine ring and imidazole rings are twisted from each other by a dihedral angle of 20.78 (2)° ( Fig. 1).
The crystal structure is stabilized by intermolecular O-H···N, O-H···O and N-H···O, hydrogen bonds. A twodimensional supramolecular architecture is formed via hydrogen-bond interactions (Table 1 and Fig. 2).

S3. Refinement
All H atoms attached to C atoms, O atoms and N atoms except H5B were fixed geometrically and treated as riding with C-H = 0.93 Å (aromatic), O-H = 0.82 Å and N-H = 0.86 Å with U iso (H) = 1.2U eq (C and N) or U iso (H) = 1.5U eq (O).
H5B atom of H 2 O were located in difference Fourier maps.

Figure 1
A view of the title compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. Unlabelled atoms are related to labelled atoms by the symmetry code ( -x+1, -y+1, -z).

Figure 2
The crystal packing of the title compound viewed along the b axis and all hydrogen atoms not involved in hydrogen bonding (dashed lines) were omitted for clarity.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq