catena-Poly[{μ-N′-[2-(carboxylatomethoxy)benzylidene]-2-hydroxybenzohydrazidato}(methanol-κO)nickel(II)]

In the title compound, [Ni(C16H12N2O5)(CH3OH)]n, the unique NiII ion is coordinated in a distorted octahedral environment by three O atoms and one N atom from a symmetry-unique ligand in the equatorial sites. Coordination of the axial sites is provided by an O atom of a symmetry-unique methanol ligand and an O atom of a carboxylate group from a symmetry-related ligand, thus generating a one-dimensional polymer parallel to [010]. In the crystal, O—H⋯N hydrogen bonds and π–π interactions, with a centroid–centroid distance of 3.693 (2) Å, form a two-dimensional network parallel to (100). In addition, weak C—H⋯O and C—H⋯N hydrogen bonds complete a three-dimensional network. An intramolecular O—H⋯O hydrogen bond is also observed.


Experimental
Crystal data [Ni(C 16 Table 1 Hydrogen-bond geometry (Å , ). Hydrazone with carboxylate groups can also form mono-and polynuclear structures under different conditions (Wu et al., 2007;Luo et al., 2010). Herein we report the synthesis and crystal structure of the title compound, (I).
Part of the one-dimensional structure of (I) is shown in Fig. 1. The unique Ni II ion is coordinated in a distorted octahedral environment by three O atoms and one N atom from a symmetry-unique ligand. One axial site is coordinated by a methanol solvent and a symmetry-related ligand provides an O atom from a carboxylate group to complete the coordination in the other axial site and generate a one-dimensional polymer parallel to [010]. In the crystal, O-H···O hydrogen bonds and π-π interactions, with a centroid-centroid distance of 3.693 (2) Å, form a two-dimensional network parallel to (100). In addition, weak C-H···O and C-H···N hydrogen bonds complete a three-dimensional network (Fig.   2). An intramolecular O-H···O hydrogen bond is also observed.

Experimental
The hydrazone ligand was synthesized according to the literature procedure (Luo et al., 2010). Nickel(II) acetate monohydrate (1 mmol) was dissolved in methanol (15 ml), to which a solution of the ligand (2.5 mmol) in dimethylformamide (15 ml) was added. The mixture was stirred for 3 h at room temperature. A light-green solution was obtained, the solution was filtered and allowed to stand at room temperature for three weeks, where upon light-green block-shaped crystals were obtained.

Refinement
All H atoms, except for H2A, H1M and H2M were placed in idealized positions and allowed to ride on their parent atoms, with C-H = 0.93-0.97Å and U iso =1.2-1.5U eq (C). The hydroxy H2A, H1M and H2M atoms were refined independently with an isotropic displacement parameters.   Part of the crystal structure with hydrogen bonds drawn as dashed lines. Only H atoms involved in hydrogen bonds are shown.

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.