[μ2-N 2,N 2′-Bis(3-methoxy-2-oxidobenzylidene)benzene-1,3-dicarbohydrazidato]bis[pyridinecopper(II)]

In the centrosymmetric dinuclear title complex, [Cu2(C24H18N4O6)(C5H5N)2], the CuII ions is tetracoordinated by two O-atoms and one N-donor of the bridging terephthalohydrazonate ligand and by one pyridine N atom, resulting in a nearly square-planar N2O2 coordination geometry with the CuII ion 0.044 (2) Å out of the mean plane (r.m.s. deviation of 0.0675 Å) of the coordinating atoms.

In the centrosymmetric dinuclear title complex, [Cu 2 (C 24 H 18 -N 4 O 6 )(C 5 H 5 N) 2 ], the Cu II ions is tetracoordinated by two Oatoms and one N-donor of the bridging terephthalohydrazonate ligand and by one pyridine N atom, resulting in a nearly square-planar N 2 O 2 coordination geometry with the Cu II ion 0.044 (2) Å out of the mean plane (r.m.s. deviation of 0.0675 Å ) of the coordinating atoms.
As show in Fig 1, we can see that the title complex contain dinuclear copper(II) skeletons showing a trans conformation (centrosymmetry). That is, one half of the dinuclear copper(II) complex constitutes the crystallographic asymmetric unit and the other half is produced by an inversion centre. In the title complex, Cu1(II) ion is coordinated by carbonyl atom O1, hydrazine atom N2 and phenol atom O2 from the moieties of the ligand H 4 L, which is hexadentate ligand that function as tetrabasic in the enol form, and N3 atom from coordinated pyridine molecule, obtaining a nearly squareplanar N 2 O 2 geometry (r.m.s deviation =0.0675 Å). The Cu II atom is shifted 0.044 (2) Å out of the square-plane. One fivemembered chelate ring (ring M 1 ) and one six-membered chelate ring (ring M 2 ) are formed by the moieties of the ligand L 4and Cu1 atom. The ring M 1 is composed of Cu1, N2, N1, C1 and O1 with r.m.s deviation of 0.0123 Å,The ring M 2 of Cu1, N2, C5, C6, C7 and O2 with r.m.s deviation of 0.0238 Å. All two chelate rings are planar. The bond lengths of Cu-N and Cu-O in the title complex are similar to those in other dinuclear copper(II) complexes (Banerjee et al., 2009;Shulgin et al., 2011;Mistri et al., 2013). The whole L 4ligand is a nearly planar (r.m.s deviation=0.0805 Å), the dihedral angle between the two benzene rings is 7.29 (29)°.

Experimental
Reagents and solvents were used as obtained without further purification. N,N′-bis(3-methoxy-2-oxybenzylidene)terephthalohydrazone (H 4 L) was synthesized according to the literature methods . H 4 L (0.0462 g, 0.1 mmol) and copper(II) chloride dihydrate (0.0342 g, 0.2 mmol) were dissolved in a mixed solution of 10 ml CH 3 OH and 5 ml DMF. The mixture was stirred for 10 minutes at room temperature and then 5 ml pyridine was slowly added.
The reaction mixture was further stirred for 4 h. After being obtained by filtration, the dark green filtrate was allowed to stand at room temperature for 15 days. The dark green prism crystals of the title complex were obtained by slow evaporation.

Refinement
All H atoms were positioned geometrically and refined using a riding model [C-H=0.93

Figure 1
The molecular structure of the title complex, showing 50% probability displacement ellipsoids and the atom numbering scheme. 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.