A second polymorph of aqua{4-chloro-2-[(pyridin-2-ylmethyl)iminomethyl]phenolato}copper(II) nitrate monohydrate

The title complex, [Cu(C13H10ClN2O)(H2O)]NO3·H2O, was obtained by the reaction of 5-chlorosalicylaldehyde, 2-(aminomethyl)pyridine and copper nitrate in methanol. The first reported polymorph of this complex was triclinic [Liang et al. (2010 ▶). Acta Cryst. E66, m40]. The present polymorph crystallized in the monoclinic space group P21/c. The CuII ion is in a square planar environment and is coordinated by one phenolate O, one imine N and one pyridine N atom of the tridentate Schiff base ligand and by one water O atom. In the crystal, molecules are linked through intermolecular O—H⋯O hydrogen bonds to form chains along the a axis.

The title complex, [Cu(C 13 H 10 ClN 2 O)(H 2 O)]NO 3 ÁH 2 O, was obtained by the reaction of 5-chlorosalicylaldehyde, 2-(aminomethyl)pyridine and copper nitrate in methanol. The first reported polymorph of this complex was triclinic [Liang et al. (2010). Acta Cryst. E66, m40]. The present polymorph crystallized in the monoclinic space group P2 1 /c. The Cu II ion is in a square planar environment and is coordinated by one phenolate O, one imine N and one pyridine N atom of the tridentate Schiff base ligand and by one water O atom. In the crystal, molecules are linked through intermolecular O-HÁ Á ÁO hydrogen bonds to form chains along the a axis.
The Cu atom is coordinated by one phenolate O, one imine N, and one pyridine N of the Schiff base ligand, and one water O atom, forming a square planar coordination. The bond lengths (Table 1) are within the normal range. In the crystal, molecules are linked through intermolecular O-H···O hydrogen bonds (Table 2), to form chains along the a axis,

Experimental
To a solution of 5-chlorosalicylaldehyde (0.156 g, 1.0 mmol), 2-aminomethylpyridine (0.108 g, 1.0 mmol) in 30 ml me thanol was added slowly a solution of copper nitrate (0.241 g, 1.0 mmol) in methanol. The mixture was stirred for 2 h at room temperature to give a blue solution, which was filtered and the filtrate was left to stand at room temperature. Blue block crystals suitable for X-ray diffraction were obtained by slow evaporation.

Refinement
The water H atoms were located in a difference map and refined with distances restraint of O-H = 0.85 (1) Å and H···H = 1.37 (2) Å. Other H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.97 Å.

Figure 2
The packing of (I), viewed down the b axis. Hydrogen bonds are drawn as dashed lines. H atoms not involved in hydrogen bonding have been omitted.

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.