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

The asymmetric unit of the title compound, [Cu(C21H24N2O2)]·H2O, comprises half of a Schiff base complex and half of a water molecule. The whole compound is generated by crystallographic twofold rotation symmetry. The geometry around the CuII atom, located on a twofold axis, is distorted square-planar, which is supported by the N2O2 donor atoms of the coordinating Schiff base ligand. The dihedral angle between the symmetry-related benzene rings is 47.5 (4)°. In the crystal, the water molecule that is hydrogen bonded to the coordinated O atoms links the molecules via O—H⋯O interactions into chains parallel to [001]. The crystal structure is further stabilized by C—H⋯π interactions, and by π–π interactions involving inversion-related chelate rings [centroid–centroid distance = 3.480 (4) Å].

The asymmetric unit of the title compound, [Cu(C 21 H 24 -N 2 O 2 )]ÁH 2 O, comprises half of a Schiff base complex and half of a water molecule. The whole compound is generated by crystallographic twofold rotation symmetry. The geometry around the Cu II atom, located on a twofold axis, is distorted square-planar, which is supported by the N 2 O 2 donor atoms of the coordinating Schiff base ligand. The dihedral angle between the symmetry-related benzene rings is 47.5 (4) . In the crystal, the water molecule that is hydrogen bonded to the coordinated O atoms links the molecules via O-HÁ Á ÁO interactions into chains parallel to [001]. The crystal structure is further stabilized by C-HÁ Á Á interactions, and byinteractions involving inversion-related chelate rings [centroid-centroid distance = 3.480 (4) Å ].
The asymmetric unit of the title compound, Fig. 1, comprises half of a Schiff base complex and half a water molecule.
The Cu1 and C9 atoms of the complex and the O atom of the water molecule lie on a two-fold rotation axis which generates the whole complex. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to those reported for related structures (Kargar et al., 2012;Kargar et al., 2011;Ghaemi et al., (2011). The geometry around the Cu II atom is distorted square-planar which is supported by the N 2 O 2 donor atoms of the coordinated Schiff base ligand. The dihedral angle between the substituted benzene rings is 47.5 (4)°.

Experimental
The title compound was synthesized by adding 5-methyl-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 water H atom was located in a difference Fourier map and refined as a riding atom with U iso (H) = 1.5U eq (O). The Cbound 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 x U eq (C), where k = 1.5 for CH 3 H-atoms, and = 1.2 for other Hatoms.

Figure 1
A view of the molecular structure of the title compound, with the atom numbering. The displacement ellipsoids are drawn at the 40% probability level. The O-H···O hydrogen bonds are shown as dashed lines (see Table 1 for details; symmetry code for suffix A = -x+1, y, -z-1/2).   Table 1 for details; only the H atoms involved in these interactions are shown]. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.03 e Å −3 Δρ min = −0.96 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.