Crystal structures of dimethyl 5-iodoisophthalate and dimethyl 5-ethynylisophthalate

In dimethyl 5-iodoisophthalate, C10H9IO4, (I), the planes through the methyl carboxylate moieties are tilted with respect to the benzene ring, whereas the molecular framework of dimethyl 5-ethynylisophthalate, C12H10O4, (II), is perfectly planar. The crystal structure of (I) is stabilized by a three-dimensional supramolecular network comprising C—H...O=C hydrogen bonds, as well as I...O=C interactions. In the crystal of (II), the molecules are connected via C—Hethynyl...O=C hydrogen bonds to infinite strands. Moreover, π–π arene stacking interactions connect the molecular chains into two-dimensional supramolecular aggregates.