[4,4′-(Ethane-1,2-diyldinitrilo)bis(pent-2-en-2-olato)]copper(II) 0.25-hydrate

In the title compound, [Cu(C12H18N2O2)]·0.25H2O, the coordination of the O,N,N′,O′-tetradentate ligand results in a cis-CuN2O2 square-planar geometry for the metal ion and the presence of two six-membered and one five-membered chelate rings. The complete complex molecule is close to planar (r.m.s. deviation = 0.047 Å). The uncoordinated water molecule (O-atom site symmetry 2) was modelled as half occupied. In the crystal, C—H⋯Ow and Ow—H⋯O (w = water) hydrogen bonds link the components into layers parallel to ab plane.

In the title compound, [Cu(C 12 H 18 N 2 O 2 )]Á0.25H 2 O, the coordination of the O,N,N 0 ,O 0 -tetradentate ligand results in a cis-CuN 2 O 2 square-planar geometry for the metal ion and the presence of two six-membered and one five-membered chelate rings. The complete complex molecule is close to planar (r.m.s. deviation = 0.047 Å ). The uncoordinated water molecule (O-atom site symmetry 2) was modelled as half occupied. In the crystal, C-HÁ Á ÁO w and O w -HÁ Á ÁO (w = water) hydrogen bonds link the components into layers parallel to ab plane.

Related literature
For background to Schiff bases and their complexes, see: Aslam et al. (2012).
MA expresses his gratitude to the PCSIR Laboratories Complex, Karachi, the Department of Chemistry, University of Karachi, and the Department of Chemistry, GC University, Lahore, for providing financial support, research facilities and X-ray diffraction facilities, respectively. MNA also acknowledges Professor Helen Stoeckli-Evans, Switzerland, for guidance about the final refinement.   (Table. 2, Fig. 2).

Experimental
A methanolic solution of copper (II) chloride dihydrated (1 mol) (5 ml) was slowly added to a methanolic solution of 4-{[2-((1-methyl-3-oxobutylidene)amino)ethyl]imino}-2-pentanone (1 mol) (100 ml) and refluxed with stirring for 45 min. The pH was gradually raised to achieve the suitable pH for the formulation of the complex by the drop wise addition of 1 M NaOH solution. Now the reaction mixture was refluxed with stirring for 90 min. After cooling, the mixture was concentrated to one third under reduced pressure. The concentrated reaction mixture was kept at room temperature and black crystals were obtained after six days. The crystalline product was collected, washed with cooled methanol, recrystallized from ethylacetate and methanol (1:1) mixture and dried to afford the title compound in 73.1% yield. Slow evaporation of a methanol solution afforded dark brown blocks of (I).

Figure 1
The molecular structure of (I) with 50% displacement ellipsoids.

sup-3
Acta Cryst. (2012). E68, m670 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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 )
x y z U iso */U eq Occ.  (2)