Poly[[tris(μ3-2-oxidopyridinium-3-carboxylato)manganese(II)sodium(I)] monohydrate]

In the crystal structure of the title compound, {[MnNa(C6H4NO3)3]·H2O}n, the MnII cation is located on a threefold rotation axis and is chelated by three 2-oxidopyridinium-3-carboxylate (opc) anions in an octahedal coordination. The NaI cation is located on a threefold rotation axis and is surrounded by six O atoms from three opc anions. The opc anions link the Mn and Na cations, forming a three-dimensional polymeric structure. The uncoordinated water molecule, located on a threefold rotation axis, is equally disordered over two sites. The three-dimensional network is consolidated by N—H⋯O hydrogen bonds.

In the crystal structure of the title compound, {[MnNa(C 6 H 4 -NO 3 ) 3 ]ÁH 2 O} n , the Mn II cation is located on a threefold rotation axis and is chelated by three 2-oxidopyridinium-3carboxylate (opc) anions in an octahedal coordination. The Na I cation is located on a threefold rotation axis and is surrounded by six O atoms from three opc anions. The opc anions link the Mn and Na cations, forming a threedimensional polymeric structure. The uncoordinated water molecule, located on a threefold rotation axis, is equally disordered over two sites. The three-dimensional network is consolidated by N-HÁ Á ÁO hydrogen bonds.
In the crystal structure the Mn II cation is located in a three-fold ratation axis and is chelated by three 2-oxidopyridinium-3-carboxylate (opc) anions in a distorted anti-triprism geometry (Fig. 1). The Na I cation is located on the same three-fold rotation axis and is surrounded by six O atoms from three opc anions (Table 1). The opc anions link the Mn and Na cations to form the three dimensional polymeric structure.
The shorter C-O bond distance of 1.251 (4) Å is observed between the deprotonated hydroxy group and pyridinium ring. This is similar to those found in the related complexes of oxidopyridinium-carboxylate (Yao et al., 2004;Yan & Hu, 2007a,b;Wen & Liu, 2007;Zhang et al. 2009a,b), it is also consistent with that found in hydroxy-pyridinecarboxylate complex (Quintal et al. 2002). This finding suggests the electron delocalization between pyridine ring and hydroxy group. But this shorter C-O bond is much different from the C-O bond distance of ca. 1.35 Å between benzene ring and hydroxy-O atom found in hydroxy-benzencarboxylic acid (Munshi & Guru Row, 2006) and in hydroxy-benzenecarboxylate complexes of metals (Su & Xu, 2005;Li et al., 2005).
The lattice water molecule located on the three-fold rotation axis is disordered over two sites with o.5 occupancies for each component. The N-H···O hydrogen bondings are present in the polymeric structure. No π-π stacking is observed in the crystal structure.
Experimental 2-Hydroxy-pyridine-3-carboxylic acid (0.13 g, 1 mmol), NaOH (0.04 g, 1 mmol), imidazole (0.14 g, 2 mmol) and Mn(NO 3 ) 2 (0.18 g, 1 mmol) and water (8 ml) and ethanol (2 ml) were sealed in a 25 ml stainless steel reactor with a Teflon liner. The reaction system was heated at 433 K for 9 h. After the mixture was cooled to room temperature the single crystals of the title complex were obtained.

Refinement
The lattice water molecule is disordered over two sites with 0.5 occupancy for each component, the water H atom was placed in a chemical sensitive position and refined in a riding mode with U iso (H) = 1.2U eq (O1W). The H atom bonded to the pyridine N was located in a difference Fourier map and refined as riding in as-found relative position with U iso (H) = 1.2U eq (N). Other H atoms were placed in calculated positions with C-H = 0.93 and refined in riding mode with U iso (H) = 1.2U eq (C).  Fig. 1. The coordination environment around a Mn cation and a Na cation with 30% probability displacement ellipsoids (arbitrary spheres for H atoms) [symmetry codes: (i) 1-y, x-y, z; (ii) 1-x+y, 1-x, z].

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.