Bis[4-chloro-2-(iminomethyl)phenolato]nickel(II)

In the title centrosymmetric mononuclear nickel(II) complex, [Ni(C7H5ClNO)2], the NiII ion, lying on an inversion center, is four-coordinated by two O and two imine N atoms from two 4-chloro-2-iminomethylphenolate ligands, forming a distorted square-planar geometry. In the crystal structure, molecules are linked into a two-dimensional network parallel to the bc plane by C—H⋯O hydrogen bonds.

In the title centrosymmetric mononuclear nickel(II) complex, [Ni(C 7 H 5 ClNO) 2 ], the Ni II ion, lying on an inversion center, is four-coordinated by two O and two imine N atoms from two 4chloro-2-iminomethylphenolate ligands, forming a distorted square-planar geometry. In the crystal structure, molecules are linked into a two-dimensional network parallel to the bc plane by C-HÁ Á ÁO hydrogen bonds.
The author acknowledges Liaodong University for funding this study.

S1. Comment
Recently, the author has reported the crystal structure of a Schiff base nickel(II) complex (Hong, 2007). As an extension of the work on the structural investigation of nickel(II) complexes, the title complex is reported here.
The title compound is a centrosymmetric mononuclear nickel(II) complex ( Fig. 1), which is similar to those reported previously (Kamenar et al., 1990). The Ni atom, lying on the inversion center, is four-coordinated by two O and two imine N atoms from two 4-chloro-2-iminomethylphenol ligands, forming a square-planar geometry. The bond lengths (Table 1) related to the metal centre are comparable to the values in similar nickel(II) complexes (Zhou et al., 2004;Li et al., 2005;Li et al., 2007).
In the crystal structure, the molecules are linked into a two-dimensional network parallel to the bc plane by C-H···O hydrogen bonds (Table 1).

S2. Experimental
5-Chlorosalicylaldehyde (1.0 mmol, 156.6 mg) and Ni(CH 3 COO) 2 .4H 2 O (0.5 mmol, 125.0 mg) were dissolved in methanol solution containing a small quantity of ammonia (30 ml). The mixture was stirred at room temperature for 30 min to give a clear brown solution. After keeping the solution in air for a few days, brown block-shaped crystals were formed.

S3. Refinement
Atom H1 was located from a difference Fourier map and refined isotropically, with the N1-H1 distance restrained to 0.90 (1) Å. Other H atoms were placed in idealized positions and constrained to ride on their parent atoms with C-H distances of 0.93 Å, and with U iso (H) set to 1.2U eq (C).

Figure 1
The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme. Unlabelled atoms are related to labelled atoms by the symmetry operation (1 -x, 1 -y, -z). 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 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.