Two isomeric butadiene-N-(acetoxy-phenyl)maleimide Diels-Alder adducts: Supramolecular structure directed by C - H⋯X (X = O and π) hydrogen bonds and perpendicular dipole carbonyl-carbonyl inter-actions

The molecular and supramolecular structures of 2-(1,3-dioxo-2,3,3a,4,7,7a- hexahydro-1H-isoindol-2-yl)phenyl acetate, C₁₆-H₁₅NO ₄, (I), and its para isomer, 4-(1,3-dioxo-2,3,3a,4,7,7a-hexahydro-1H- isoindol-2-yl)phenyl acetate, (II), are reported. The torsion angle between the succinimide and benzene rings depends on the position of the acetoxy substitution [89.7(1) and 61.9(1)° for (I) and (II), respectively]. The twist of the acetoxy group relative to the mean plane of the benzene ring is almost independent of the acetoxy position [66.0(1) and 70.0(1)°]. Packing interactions for both compounds include soft C - H⋯X (X = O and Ph) interactions, forming chains of centrosymmetric dimers and interlinked chains for (I) and (II), respectively. In addition, three perpendicular dipole C=O⋯C=O interactions contribute to the supramolecular structure of (II).