5‐Iodobenzofurazan 1‐oxide: polymorphs,pseudosymmetry and disorder

5‐Iodobenzofurazan 1‐oxide (systematic name: 5‐iodobenzo‐1,2,5‐oxadiazole 1‐oxide), C₆H₃IN₂O₂, occurs in two polymorphic forms, both monoclinic in P2₁/c with Z′ = 2. The intermolecular interactions in the two polymorphs are quite different. In polymorph (I), there are strong intermolecular I...O interactions, with I...O distances of 3.114 (8) and 3.045 (8) Å. In polymorph (II), there are strong intermolecular I...N interactions, with I...N distances of 3.163 (4) and 3.175 (5) Å. In (I), there is about 15% disorder in one molecule and about 5% in the other. In both polymorphs, there are pseudosymmetric relationships between the crystallographically independent molecules.