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

In dimethyl 5-iodo­isophthalate, C(10)H(9)IO(4), (I), the planes through the methyl carboxyl­ate moieties are tilted with respect to the benzene ring, whereas the mol­ecular framework of dimethyl 5-ethynylisophthalate, C(12)H(10)O(4), (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—H(ethyn­yl)⋯O=C hydrogen bonds to infinite strands. Moreover, π–π arene stacking inter­actions connect the mol­ecular chains into two-dimensional supra­molecular aggregates.