Diaquabis[2-(2-hydroxyethyl)pyridine-κ2 N,O]cobalt(II) dichloride

In the title salt, [Co(C7H9NO)2(H2O)2]Cl2, the CoII cation, located on an inversion center, is N,O-chelated by two hydroxyethylpyridine ligands and coordinated by two water molecules in a distorted O4N2 octahedral geometry. In the crystal, the Cl− anions link with the complex cations via O—H⋯Cl hydrogen bonds, forming a three-dimensional supramolecular architecture. π–π stacking is observed between the pyridine rings of adjacent molecules [centroid–centroid distance = 3.5810 (11) Å].

In the title salt, [Co(C 7 H 9 NO) 2 (H 2 O) 2 ]Cl 2 , the Co II cation, located on an inversion center, is N,O-chelated by two hydroxyethylpyridine ligands and coordinated by two water molecules in a distorted O 4 N 2 octahedral geometry. In the crystal, the Cl À anions link with the complex cations via O-HÁ Á ÁCl hydrogen bonds, forming a three-dimensional supramolecular architecture.stacking is observed between the pyridine rings of adjacent molecules [centroid-centroid distance = 3.5810 (11) Å ].

Merazig Comment
Pyridine derivatives ligands have the potential to be used in the synthesis of supramolecular materials, particularly transition metal coordination polymers (Sanudo et al., 2003;Boskovic et al., 2002). A few complexes containing L (L =2 (2-hydroxyethyl)pyridine) have been studied for years, because this ligand has a versatile coordination activities and bridging function (Kong et al., 2009;Mobin et al., 2010). We report here the synthesis and crystal structure of the title compound.
The complex comprises two L (L = 2-(2-hydroxyethyl)pyridine) ligands, one Co II ion, two aqua ligands and uncoordinated Cl anions (Fig. 1). The coordination geometry around the Co center is octahedral with a CoN 2 O 4 ligand set (Table 1). The bis L ligands coordinate to the Co(II) ions through the nitrogen atom of pyridine ring and the oxygen atom of hydroxyl group, creating a chelate ring. The octahedral geometries are completed by two trans aqua ligands at axial positions.

Experimental
The title compound was prepared by reaction of 2 (2-hydroxyethyl)pyridine (10.0 mmol, 1.67 g) in a mixture of ethanolwater (V/V = 1:1) and CoCl 2 .6H 2 O (10.0 mmol, 2.50 g), the solution was maintained at 313 K under agitation during 24 h at room temperature. Pink crystals were obtained by slow evaporation of the solvents within 3 weeks.

Figure 3
A part of the crystal packing showing π-π stacking interactions between the pyridine rings (dashed lines). Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles 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.