{4,4′-Dimethyl-2,2′-[(2,2-dimethylpropane-1,3-diyl)bis(nitrilomethanylylidene)]diphenolato}nickel(II) monohydrate

In the title compound, [Ni(C21H24N2O2)]·H2O, both the complex molecule and the water molecule lie on a twofold rotation axis. The NiII ion is coordinated in a distorted square-planar geometry by the tetradentate ligand. The dihedral angle between the two symmetry-related benzene rings is 47.12 (8)°. In the crystal, pairs of symmetry-related O—H⋯O hydrogen bonds form R 2 2(6) ring motifs. In addition, there are weak intermolecular C—H⋯O hydrogen bonds, and π–π stacking interactions with a centroid–centroid distance of 3.4760 (8) Å.

In the title compound, [Ni(C 21 H 24 N 2 O 2 )]ÁH 2 O, both the complex molecule and the water molecule lie on a twofold rotation axis. The Ni II ion is coordinated in a distorted squareplanar geometry by the tetradentate ligand. The dihedral angle between the two symmetry-related benzene rings is 47.12 (8) . In the crystal, pairs of symmetry-related O-HÁ Á ÁO hydrogen bonds form R 2 2 (6) ring motifs. In addition, there are weak intermolecular C-HÁ Á ÁO hydrogen bonds, andstacking interactions with a centroid-centroid distance of 3.4760 (8) Å .

Comment
In continuation of our work on the crystal structures of a Schiff base ligands and complexes Kargar et al., ,2011Rayati et al., 2011;Kia et al., 2010), we have determined the X-ray structure of the title compound.
The molecular structure of the title compound is ahown in Fig. 1. The asymmetric unit comprises half of Schiff base complex and half a water molecule. The Ni II ion, the central carbon atom of the diamine segment (C10) and the O atom of water molecule lie on a two-fold rotation axis. The coordination geometry of Ni1 is distorted square-planar formed by the tetradentate ligand. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to related structures Rayati et al., 2011). The dihedral angle between the two symmetry related benzene rings is 47.12 (8)°. A pair of symmetry related intermolecular O-H···O hydrogen bonds form an R 2 2 (6) ring motif (Bernstein et al., 1995). In the crystal, molecules are linked through weak intermolecular C-H···O interactions.

Experimental
The title compound was synthesized by adding bis(5-methylsalicylaldehyde)-2,2-dimethyl-1,3-propanediimine (2 mmol) to a solution of nickel(II) chloride hexahydrate (2.1 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for half an hour. The resultant solution was filtered. Yellow single crystals of the title compound suitable for X-ray structure determination were recrystallized from an ethanol solution of the title compound by slow evaporation of the solvent at room temperature over several days.

Refinement
Hydrogen atoms bonded to C atoms were positioned geometrically with C-H = 0.93-0.97 Å and included in a riding model approximation with U iso (H) = 1.2 or 1.5 U eq (C) The unique water H atom was located in a difference Fourier map and then constrained to ride to the parent atom with U iso (H) = 1.5 U eq (O). A rotating group model was used only for the benzene-substituent methyl group.  {4,4'-Dimethyl-2,2'-[(2,2-dimethylpropane-1,3-diyl)bis(nitrilomethanylylidene)]diphenolato}nickel(II) monohydrate Crystal data [Ni(C 21

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.