2-(4-chlorophenyl)-5-(4-nitrophenyl)-4,7-dihydropyrazolo[1,5-a]pyrimidine-3,6-dicarbaldehyde: a chain of rings built from N-H...O and C-H...O hydrogen bonds.

In the title compound, C20H13ClN4O4, the six-membered heterocyclic ring is planar and the molecular dimensions provide evidence for polarization of the molecular-electronic structure. Molecules are linked into a chain of rings by a combination of N-H...O and C-H...O hydrogen bonds, but the nitro group does not participate in the supramolecular aggregation. This study illustrates the marked influence of peripheral substituents on the pattern of hydrogen-bonded aggregation in compounds of this type.