Bis(2-hydroxyiminomethyl-6-methoxyphenolato-κ2 O 1,N)cobalt(II)

In the title compound, [Co(C8H8NO3)2], the CoII atom lies on a centre of inversion and is coordinated in a slightly distorted square-planar geometry by two N and two O atoms from the 2-hydroxyiminomethyl-6-methoxyphenolate ligands. Intramolecular O—H⋯O hydrogen bonds are formed and the complexes form stacks along the b axis, with an interplanar separation of 3.332 (1) Å between complexes. Pairs of C—H⋯O contacts are formed between complexes in neighbouring stacks.

In the title compound, [Co(C 8 H 8 NO 3 ) 2 ], the Co II atom lies on a centre of inversion and is coordinated in a slightly distorted square-planar geometry by two N and two O atoms from the 2-hydroxyiminomethyl-6-methoxyphenolate ligands. Intramolecular O-HÁ Á ÁO hydrogen bonds are formed and the complexes form stacks along the b axis, with an interplanar separation of 3.332 (1) Å between complexes. Pairs of C-HÁ Á ÁO contacts are formed between complexes in neighbouring stacks.

Experimental
A solution of (0.152 g, 1.0 mmol) 2-hydroxy-3-methoxy-benzaldehyde oxime and (0.056 g, 1 mmol) potassium hydroxide in 20 ml absolute methanol was added slowly to a solution of CoNO 3 .6H 2 O (0.145 g, 0.5 mmol) in methanol. The mixture was stirred for 1 h at room temperature to give a red solution which was filtered and the filtrate was left to stand at room temperature. Red block crystals suitable for were obtained by slow evaporation Yield: 80.1 % (based on Co). Elemental analysis calculated: C 49.12, H 4.12, N 7.16 %; found: C 48.99, H 4.21, N 7.22 %.

Refinement
H atoms were positioned geometrically and refined with a riding model, with distances 0.96 (CH 3 ) or 0.93 Å (aromatic ring), and with U iso (H) = 1.2 U eq (aromatic ring) or U iso (H) = 1.5 U eq (CH 3 ), and with O-H distance 0.82 Å and U iso (H) = 1.5 U eq (O).
Crystal data [Co(C 8 H 8

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.