Triclinic and orthorhombic polymorphs of 2-iodo-4-nitroaniline: interplay of hydrogen bonds, nitro center dot center dot center dot I interactions and aromatic pi-pi-stacking interactions

In the triclinic polymorph of 2-iodo-4-nitroaniline, C6H5IN2O2, space group P (1) over bar, the molecules are linked by paired N-H . . .O hydrogen bonds into C(8)[R-2(2)(6)] chains of rings. These chains are linked into sheets by nitro . . . I interactions, and the sheets are pairwise linked by aromatic pi-pi -stacking interactions. In the orthorhombic polymorph, space group Pbca, the molecules are linked by single N-H . . .O hydrogen bonds into spiral C(8) chains; the chains are linked by nitro . . . O interactions into sheets, each of which is linked to its two immediate neighbours by aromatic pi-pi -stacking interactions, so producing a continuous three-dimensional structure.