2-(2,4-Dichlorophenoxy)-N′-[2-(2,4-dichlorophenoxy)acetyl]acetohydrazide

In the crystal of the title compound, the molecules are linked into chains by N—H⋯O hydrogen bonds. The chains are interlinked by short Cl⋯N contacts.

The complete molecule of the title compound, C 16 H 12 Cl 4 N 2 O 4 , is generated by a crystallographic centre of symmetry. In the crystal, N-HÁ Á ÁO hydrogen bonds link the molecules into [010] chains featuring R 2 2 (10) loops. The chains are crosslinked by short ClÁ Á ÁN contacts [3.224 (2) Å ].

Structure description
Diacylhydrazines have insecticidal activities (Wang et al., 2017) and can also be used to recover metal ions from solution (Chekanova et al., 2004;Radushev et al., 2007). In addition, they are precursors in the synthesis of biologically active heterocycles (Zarei 2017;Stabile et al., 2010). As part of our studies in this area, we now describe the synthesis and structure of the title compound, C 16 H 12 Cl 4 N 2 O 4 (I). The asymmetric unit consists of half a molecule, which is completed by inversion symmetry centred in the middle of the central N-N bond (Fig. 1).

data reports
In the crystal, each molecule is involved in four N-HÁ Á ÁO hydrogen-bonding contacts, donating two and accepting two bonds, leading to the formation of ribbons propagating parallel to [010] (Table 1, Fig. 2). The ribbons are linked by short ClÁ Á ÁN contacts perpendicular to the plane of the ribbons and roughly in the c-axis direction. The contact involves the para Cl atom of the 2,4-dichlorophenoxy group and the nitrogen atom of the N 0 -acetylacetohydrazide group, with a Cl2Á Á ÁN1 distance of 3.224 (2) Å (sum of van der Waals' radii = 3.30 Å ).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Table 1 Hydrogen-bond geometry (Å , ).

Figure 1
The molecular structure of (I) showing 50% displacement ellipsoids. Symmetry code: (i) 1 À x, 2 À y, 1 À z. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.51 e Å −3 Δρ min = −0.42 e Å −3 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. The H atoms were positioned geometrically (N-H = 0.86, C-H = 0.93-0.96 Å) and refined using a riding model with U iso (H) = 1.2U eq (C,N).