Three-dimensional aggregation in 2-hydroxy-3-iodo-5-nitrobenzaldehyde involving C-H...O, iodo-nitro and aromatic pi-pi stacking interactions, and isolated dimers in disordered 2,4-diiodo-6-nitroanisole.

In 2-hydroxy-3-iodo-5-nitrobenzaldehyde, C(7)H(4)INO(4), the molecules are linked into sheets by a combination of C-H.O hydrogen bonds and two-centre iodo-nitro interactions, and these sheets are linked by aromatic pi-pi stacking interactions. Molecules of 2,4-diiodo-6-nitroanisole, C(7)H(5)I(2)NO(3), are disordered, with the nitro group and one of the I substituents each occupying common sets of sites with 0.5 occupancy. The molecules are linked into isolated centrosymmetric dimeric units by a single iodo-nitro interaction.