{4,4′-Dimethoxy-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethanylylidene)]diphenolato}copper(II) monohydrate

The asymmetric unit of the title compound, [Cu(C21H24N2O4)]·H2O, comprises half of a Schiff base complex and a water molecule. The CuII atom, water molecule and one C atom of the central propylene segment are located on a twofold rotation axis. The geometry around the CuII atom is distorted square-planar, supported by the N2O2 donor atoms of the coordinating ligand. The dihedral angle between the symmetry-related benzene rings is 42.56 (19)°. In the crystal, O—H⋯O hydrogen bonds involving the water molecule make an R 2 1(6) ring motif. Complex molecules are linked into a chain along the c axis via C—H⋯O interactions.

The asymmetric unit of the title compound, [Cu(C 21 H 24-N 2 O 4 )]ÁH 2 O, comprises half of a Schiff base complex and a water molecule. The Cu II atom, water molecule and one C atom of the central propylene segment are located on a twofold rotation axis. The geometry around the Cu II atom is distorted square-planar, supported by the N 2 O 2 donor atoms of the coordinating ligand. The dihedral angle between the symmetry-related benzene rings is 42.56 (19) . In the crystal, O-HÁ Á ÁO hydrogen bonds involving the water molecule make an R 2 1 (6) ring motif. Complex molecules are linked into a chain along the c axis via C-HÁ Á ÁO interactions.
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 Schiff base complexes are one of the most important stereochemical models in transition metal coordination chemistry, with the ease of preparation and structural variations (Granovski et al., 1993;Blower et al., (1998). In continuation of our work on the crystal structures of Schiff base metal complexes (Kargar et al., 2012;Kargar et al., 2011;Ghaemi, et al., (2011), we determined the X-ray structure of the title compound.
The asymmetric unit of the title compound ( Fig. 1) comprises a a half of Schiff base complex. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to the related structure (Kargar et al., 2012;Kargar et al., 2011;Ghaemi, et al., (2011). The geometry around Cu II is a distorted square-planar which is supported by the N 2 O 2 donor atoms of the coordinated Schiff base ligand (Table 1). The dihedral angle between the substituted benzene rings is 42.56 (19)°. Interamolecular O-H···O hydrogen bonds make R 1 2 (6) ring motif (Bernstein et al., 1995). The dihedral angle between the symmetry-related benzene rings is 45.54 (19)°. In the crystal structure the molecules are linked together along the c axis, forming a chain through the intermolecular C-H···O interactions (Table 2, Fig. 2).

Experimental
The title compound was synthesized by adding 5-methoxy-salicylaldehyde-2,2-dimethyl-1, 3-propanediamine (2 mmol) to a solution of CuCl 2 . 4H 2 O (2.1 mmol) in ethanol (30 mL). The mixture was refluxed with stirring for 30 min. The resultant solution was filtered. Dark-green single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation of the solvents at room temperature over several days.

Refinement
The H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93, 0.96 and 0.97 Å for CH, CH 3 and CH 2 H-atoms, respectively, with U iso (H) = k × U eq (C), where k = 1.5 for CH 3 H-atoms, and k = 1.2 for all other H-atoms.

Computing details
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.28 e Å −3 Δρ min = −0.36 e Å −3 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.