Di-μ-acetato-κ4 O:O-bis({N′-[(E)-phenyl(pyridin-2-yl-κN)methylidene]benzohydrazidato-κ2 N′,O}copper(II))

The binuclear molecule of the title compound, [Cu2(C19H14N3O)2(CH3COO)2], resides on a crystallographic inversion centre. It has an E conformation with respect to the azomethine double bond and a Z conformation about the amide C=N bond. The CuII atom has a slightly distorted square-pyramidal coordination geometry. The crystal packing involves intermolecular C—H⋯O, C—H⋯N and C—H⋯π and two types of π–π interactions, with centroid–centroid distances of 3.9958 (10) and 3.7016 (13) Å.

The binuclear molecule of the title compound, [Cu 2 (C 19 H 14 -N 3 O) 2 (CH 3 COO) 2 ], resides on a crystallographic inversion centre. It has an E conformation with respect to the azomethine double bond and a Z conformation about the amide C N bond. The Cu II atom has a slightly distorted square-pyramidal coordination geometry. The crystal packing involves intermolecular C-HÁ Á ÁO, C-HÁ Á ÁN and C-HÁ Á Á and two types ofinteractions, with centroid-centroid distances of 3.9958 (10) and 3.7016 (13) Å .
A non-conventional intermolecular hydrogen bond (Fig. 3) is present in the molecular system between the H atoms attached to the C8, C15 atoms and O1, O2 aoms of another molecule with D···A distances of 3.416 (2) and 3.116 (3) Å respectively (Table 1). Moreover, there are C-H···π interactions between the H atoms attached at the C1, C3, C12 and C21 atoms and the corresponding aromatic and metal chelate rings of the same or another molecule ( Fig. 4) with the minimum distance of 3.170 (2) Å between the carbon atoms and the corresponding rings involving interactions. There are two types of π-π interactions within the dimeric molecule (T-shaped arrangement) and also between the adjacent molecules (slipped arrangement) with the centroid-centroid distances of 3.9958 (10) and 3.7016 (13) Å respectively between the rings involving interactions as shown in Fig. 5.
Packing of molecules ( Fig. 6) is predominantly favored by two types of non-classical intermolecular hydrogen bonding and C-H···π interactions involving the H atoms from C3 and C12 atoms and a π-π interaction between the adjacent molecules in slipped arrangement.

Experimental
The title complex was prepared by adapting a reported procedure (Mangalam et al., 2010) by refluxing a mixture of methanolic solutions of N′-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide (0.301 g, 1 mmol) and Cu(OAc) 2 .H 2 O (0.199 g, 1 mmol) for three hours. After two days, green colored crystals were collected, washed with few drops of methanol and dried over P 4 O 10 in vacuo. Single crystals of the title complex suitable for X-ray analysis were obtained after two days from the mother liquor by slow evaporation.

Refinement
All H atoms on C were placed in calculated positions, guided by difference maps, with C-H bond distance of 0.93-0.96 Å. H atoms were assigned as U iso =1.2Ueq (1.5 for Me).       Packing diagram of the compound [Cu 2 N 6 O 6 C 42 H 34 ] along a axis.

Di-µ-acetato-κ 4 O:O-bis({N′-[(E)-phenyl(pyridin-2-ylκN)methylidene]benzohydrazidato-κ 2 N′,O}copper(II))
Crystal data 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.