3,22-Dioxa-11,14-diazapentacyclo[12.8.0.02,11.05,10.015,20]docosa-5(10),6,8,15(20),16,18-hexaene-4,21-dione

In the title compound, C18H14N2O4, the piperazine ring adopts a chair conformation and the dihedral angle between the aromatic rings is 13.09 (9)°. In the crystal, molecules are linked along the c axis by C—H⋯π and N⋯π [H(N)–centroid distances = 2.8030 (2) and 3.376 (2) Å] interactions between neighbouring molecules.

In the title compound, C 18 H 14 N 2 O 4 , the piperazine ring adopts a chair conformation and the dihedral angle between the aromatic rings is 13.09 (9) . In the crystal, molecules are linked along the c axis by C-HÁ Á Á and NÁ Á Á [H(N)-centroid distances = 2.8030 (2) and 3.376 (2) Å ] interactions between neighbouring molecules.
Cg1 is the centroid of the C6-C11 ring.

Comment
The C-H···π and π-π interactions are important noncovalent intermolecular forces in determining the crystal packing, molecular assemblies, and structures of large biological systems (Janiak, 2000). In the present work, the crystal of the title compound is generated by noncovalent interactions.
As shown in Figure 2, the neighboring molecules of title compound are arranged in a mutual head-to-tail manner by C-H···Cg1 i (Cg1 is the centroid of the C6-C11 benzene ring) interactions (black dotted lines) and N···Cg2 ii (Cg2 is the centroid of the C13-C18 benzene ring) interactions (pink dotted lines)to form infinite one-dimensional chain structure along the c axis [symmetry code: The adjacent one-dimensional chains, by van der Waals contacts, stack in a side-by-side fashion along the c axis to form three-dimensional structure (Fig. 3).

Experimental
The precursor 2,2′-(ethane-1,2-diylbis(azanediyl))dibenzoic acid (EDA) was synthesized according to literature procedures (Berger et al., 2002). The title compound was prepared by stirring a methanolic solution of EDA (300 mg, 1.0 mmol) and triethylamine (1 ml) for 10 min at room temperature. Then, 10 ml of a methanol solution containing CuCl 2 ·2H 2 O(170 mg, 1 mmol) was added to the mixture and refluxed for 2 h. The mixture was filtered and washed with methanol. The EDA-Cu compound is not achieved as predicted. However, orange single crystals of the title complex suitable for X-ray analysis were obtained after several days from the mother liquor by slow evaporation.

Refinement
All H atoms were positioned geometrically [C-H = 0.97 Å for CH 2 , 0.93 Å for CH] and refined using a riding model, with Uiso = 1.2Ueq of the parent atom.  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as small spheres of arbitrary radius.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq N1 0.5762 (