Aqua{5,5′-dimethoxy-2,2-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}nickel(II)

The title mononuclear nickel(II) complex, [Ni(C18H18N2O4)(H2O)], possesses crystallographic mirror symmetry. The Ni atom is five-coordinated in a square-pyramidal geometry, with two imine N and two phenolate O atoms of the Schiff base ligand in the square plane, and the water O atom in the axial position. In the crystal, the molecules are linked via intermolecular O—H⋯O hydrogen bonds, forming chains along the a axis.

The title mononuclear nickel(II) complex,  )(H 2 O)], possesses crystallographic mirror symmetry. The Ni atom is five-coordinated in a square-pyramidal geometry, with two imine N and two phenolate O atoms of the Schiff base ligand in the square plane, and the water O atom in the axial position. In the crystal, the molecules are linked via intermolecular O-HÁ Á ÁO hydrogen bonds, forming chains along the a axis.
Financial support from the Jiaying University research fund is gratefully acknowledged.

C. Tang
Comment Nickel(II) complexes play an important role in both bioinorganic chemistry and coordination chemistry (Suh et al., 1996;Dey et al., 2004;Angulo et al., 2001;Ramadevi et al., 2005;Edison et al., 2004). Recently, the author has reported a nickel(II) complex with a related Schiff base ligand (Tang, 2009). As a continuation of this work, the title mononuclear nickel(II) complex, Fig. 1, is reported here.
The molecule of the title complex possesses crystallographic mirror symmetry. The Ni atom in the complex is five-coordinated by two imine N and two phenolate O atoms of the Schiff base ligand, and by one water O atom, forming a squarepyramidal geometry.
In the crystal structure, the molecules are linked through intermolecular O-H···O hydrogen bonds (Table 1), forming chains along the a axis, as shown in Fig. 2.
Experimental 4-Methoxy-2-hydroxybenzaldehyde (0.2 mmol, 30.5 mg), ethane-1,2-diamine (0.1 mmol, 6.0 mg) and nickel(II) nitrate hexahydrate (0.1 mmol, 29.1 mg) were mixed in a methanol solution (20 ml). The mixture was stirred at room temperature for 30 min to give a green solution. The solution was allowed to stand in air for 5 days, yielding green block-shaped crystals of the title complex.

Refinement
Water H atoms were located from a difference Fourier map and refined isotropically, with O-H distance restrained to 0.85 (1) Å. Other H atoms were constrained to ideal geometries, with C-H = 0.93-0.97 Å and U iso (H) = 1.2U eq (C).  Crystal data [Ni(C 18

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 Rfactors(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.