Halogen bonding in 1,2-dibromo-4,5-dimethoxybenzene and 1,2-diiodo-4,5-dimethoxybenzene.

An interesting case of ;halogen-bonding-promoted' crystal structure architecture is presented. The two title compounds, C(8)H(8)Br(2)O(2) and C(8)H(8)I(2)O(2), have almost indistinguishable molecular structures but very different spatial organization, and this is mainly due to differences in the halogen-bonding interactions in which the different species present, i.e. Br and I, take part. The dibromo structure exhibits a pi-bonded columnar array involving all four independent molecules in the asymmetric unit, with intercolumnar interactions governed by C-Br...Br-C links and with no C-Br...O/N interactions present. In the diiodo structure, instead, the C-I...O synthon prevails, defining linear chains, in turn interlinked by C-I...I-C interactions.