(2,2′-Bipyridine-κ2 N,N′){N-[(2-oxidonaphthalen-1-yl-κO)methylidene]-l-valinato-κO}copper(II) trihydrate

In the title complex, [Cu(C16H15NO3)(C10H8N2)]·3H2O, the CuII atom is five coordinated by O,N,O′-donor atoms of the Schiff base ligand and by two N atoms of the 2,2′-bipyridine ligand in a distorted square-pyramidal geometry. In the crystal, molecules are linked into a two-dimensional network parallel to (011) by O—H⋯O hydrogen bonds.

The molecular structure of the title complex is shown in Fig. 1. The Cu atom is in a distorted square-pyramidal coordination geometry, defined by one N and two O atoms from the Schiff base ligand and two N atoms from a 2,2′-bipyridine ligand. The basal plane is formed by the atoms O1, O3, N1 and N3, their mean deviation from this plane is 0.0891 Å, and the Cu atom just out of this plane by 0.252 Å. The axial position of the pyramid is occupied by atom N2.
In the crystal, molecules are linked into two-dimensional network by intermolecular O-H···O hydrogen bonds (Fig. 2).
Experimental 2-Hydroxy-1-Naphthaldehyde (0.172 g, 1 mmol) was added to a methanol solution (60 ml) containing L-Valine (0.117 g, 1 mmol) and potassium hydroxide (0.056 g, 1 mmol). The mixture was stirred at 333 K for 3 h, then an aqueous solution (6 ml) of cupric acetate monohydrate (0.199 g, 1 mmol) was added dropwise and stirred for 2 h. A methanol solution (6 ml) of 2,2′-Bipyridine (0.156 g, 1 mmol) was then added dropwise and the mixture stirred for 2 h. The resulting green solution was allowed to evaporate slowly at room temperature for two weeks, yielding green block crystals.

Refinement
All H-atoms were positioned geometrically and refined using a riding model, with the following constraints: C-H = 0.93 Å, U iso (H) =1.2U eq (C) for C sp 2, C-H = 0.98 Å, U iso (H) =1.2U eq (C) for CH, C-H = 0.96 Å, U iso (H) =1.5U eq (C) for CH 3 ,  The structure of the title complex, showing 30% probability displacement ellipsoids and the atom-numbering scheme.  Two dimensional network of the title complex.

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 )