2-[2-(4-Nitro-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione

In the mol-ecular structure of the title compound, C ₂₁H ₁₅N ₃O ₄, the inter-planar angle between the benzoyl units is 89.7 (1)°. The corresponding angles between the phenyl-hydrazono and the benzoyl groups are 31.4 (3) and 60.8 (2)°, respectively. In the crystal, a strong resonance-assisted intra-molecular hydrogen bond (N - H⋯O) and a weak intra-molecular hydrogen bond (C - H⋯N) strongly affect the observed conformation of the mol-ecule. The crystal packing is determined by a strong inter-molecular hydrogen bond (N - H⋯O), giving rise to a helical chain along the a axis. In addition, two weak inter-molecular contacts (C - H⋯O) are observed.