Hydrogen-bonded chains of rings in 3-iodobenzaldehyde 2,4-dinitrophenylhydrazone and 4-iodobenzaldehyde 2,4-dinitrophenylhydrazone, and a three-dimensional framework in 4-iodobenzaldehyde 4-nitrophenylhydrazone generated by the combination of N-H...O and C-H...O hydrogen bonds with iodo-nitro interactions.

Molecules of 3- and 4-iodobenzaldehyde 2,4-dinitrophenylhydrazone, C(13)H(9)IN(4)O(4), are both effectively planar. In the crystal structure of each compound, molecules are linked by a combination of N-H...O and C-H...O hydrogen bonds into complex chains of rings, containing four and three different ring motifs, respectively; neither compound contains any iodo-nitro interactions. In 3-iodobenzaldehyde 4-nitrophenylhydrazone, C(13)H(10)IN(3)O(2), where the iodinated aryl ring is disordered over two sets of sites, the hydrogen bonds generate a chain of rings, while two independent I...O interactions generate a three-dimensional framework.