Bis[μ-N′-(5-bromo-3-methoxy-2-oxidobenzylidene)-2-hydroxybenzohydrazidato]bis[(N,N-dimethylformamide)copper(II)]

The title compound, [Cu2(C15H11BrN2O4)2(C3H7NO)2], is derived from the reaction of N′-(5-bromo-2-hydroxy-3-methoxybenzylidene)-2-hydroxybenzohydrazide and copper nitrate in a dimethylformamide solution in the presence of sodium hydroxide. The compound can be regarded as a binuclear centrosymmetric complex. In the crystal, the CuII atom is fivefold surrounded and adopts a distorted square-pyramidal coordination environment. An intramolecular O—H⋯N hydrogen bond stabilizes the molecular conformation.

The title compound, [Cu 2 (C 15 H 11 BrN 2 O 4 ) 2 (C 3 H 7 NO) 2 ], is derived from the reaction of N 0 -(5-bromo-2-hydroxy-3-methoxybenzylidene)-2-hydroxybenzohydrazide and copper nitrate in a dimethylformamide solution in the presence of sodium hydroxide. The compound can be regarded as a binuclear centrosymmetric complex. In the crystal, the Cu II atom is fivefold surrounded and adopts a distorted squarepyramidal coordination environment. An intramolecular O-HÁ Á ÁN hydrogen bond stabilizes the molecular conformation.

Experimental
Crystal data [Cu 2 (C 15 Table 1 Hydrogen-bond geometry (Å , ).  Hydrazones attract the interest of researchers due to their various biological activities and their capacity for chelating to most kind of metals. As Fig. 1 shows, the Cu II ion exists in a distorted square-pyramidal coordination geometry and it is located in the center of the coordination basal plane, which is defined by three donor atoms (O2, N1 and O3) of the hydrozone ligand and O5 atom from the DMF molecule with a mean plane deviation of 0.0367 (4) Å. The axial position is occupied by O3 atom from another asymmetric unit. The molecular conformation is stabilized by an intramolecular O -H···N hydrogen bond (Table 1).

Experimental
A solution of copper nitrate (186.2 mg, 1.0 mmol) in DMF (2 ml) was added to a solution of N′-(5-bromo-2-hydroxy-3methoxybenzylidene)-2-hydroxybenzohydrazide (361.5 mg, 1.0 mmol) in DMF (10 ml) and stirred at room temperature for 2 h before being filtered. The dark green filtrate was allow to evaperate slowly in the air for several days. Green crystals was collected by filtration and dried under vacumn, yield 59.3%.

Refinement
H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-0.99 Å, O-H = 0.82 Å and with U iso (H) = 1.2 U eq (C,O) (1.5 for methyl groups and the hydroxyl group). The methyl groups bonded to N and the hydroxyl group were allowed to rotate but not to tip.  The molecular structure of the title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms.

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 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.