(E)-1-(3-Nitrophenyl)-2-({5-[(1E)-2-(3-nitrophenyl)hydrazin-1-ylidenemethyl]-2-thienyl}methylidene)hydrazine

The title molecule, C18H14N6O4S, adopts a U-shape with the aromatic groups lying syn and oriented in the same direction as the thiophene S atom. Twists away from planarity are evident with the maximum deviation being found for a terminal nitro group: C/C/N/O = 19.0 (3)°. The conformation about each of the C=N bonds is E. In the crystal, centrosymmetrically related molecules are connected via N—H⋯Onitro hydrogen bonds, forming 14-membered {⋯HNC3NO}2 synthons. These are linked into layers via C—H⋯Onitro interactions with the primary interactions between layers being of the type C—H⋯π, where the π-system is the thiophene ring.

The title molecule, C 18 H 14 N 6 O 4 S, adopts a U-shape with the aromatic groups lying syn and oriented in the same direction as the thiophene S atom. Twists away from planarity are evident with the maximum deviation being found for a terminal nitro group: C/C/N/O = 19.0 (3) . The conformation about each of the C N bonds is E. In the crystal, centrosymmetrically related molecules are connected via N-HÁ Á ÁO nitro hydrogen bonds, forming 14-membered {Á Á ÁHNC 3 NO} 2 synthons. These are linked into layers via C-HÁ Á ÁO nitro interactions with the primary interactions between layers being of the type C-HÁ Á Á, where thesystem is the thiophene ring.
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil).
The overall molecular conformation in (I) is U-shaped as the two aromatic residues lie to the same side of the molecule and are syn, being orientated in the same direction as the thiophene-S atom, Fig In the crystal packing, centrosymmetrically related molecules associate via N-H···O nitro hydrogen bonds to result in the formation of a 14-membered {···HNC 3 NO} 2 synthon, Table 1. The dimeric aggregates are linked into a supramolecular chain along the c axis via C-H···O nitro interactions, Table 1 and Fig. 2. The chains in turn are linked into layers in the ac plane via further C-H···O nitro interactions, Table 1. The layers thus formed stack along the b axis with the primary interactions between them being of the type C-H···π where the π-system is the thiophene ring [C12-H···ring centroid(S1,C1-C4) i = 2.58 Å, C12···ring centroid i = 3.323 (2) Å with an angle subtended at H = 135 ° for symmetry operation i: x, 3/2-y, -1/2+z].
The second N5-amine H does not participate in a formal hydrogen bond. It is noted that the N4-N5-H residues lie in the interlayer region and are in relative close proximity [e.g. N5-H···N4 ii = 2.87 Å] but steric constraints preclude a closer approach of these groups to allow a hydrogen bonding interaction.

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.95 Å) and refined as riding with U iso (H) = 1.2U eq (C). The N-bound H atoms were located from a difference map and refined with U iso (H) = 1.5U eq (N). Fig. 1. The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level.  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 > 2σ(F 2 ) is used only for calculating Rfactors(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.