CO…H-C interactions as packing motifs in crystals. Part 1. Structure and conformation of N-(methyl)-benzyl-3-spiro-cycloalkylopyrrolidine-2,5-diones

A set of six N-benzyl-3-spiro-succinimides with evaluated anticonvulsant activity has been crystallographically studied. In all crystals, in the absence of strong H-bond donors, only weak H-bonds of C-H…OC have been found as intermolecular interactions. For six crystals, two main packing motifs of the strongest interactions of C(sp3)-H…OC have formed two alternative supramolecular synthons. Additionally in all crystals, interactions with aromatic donors have been identified. The analogy in the chemical formulas of the studied species has been complemented by the similarity in the H-bonding patterns in the crystals. However, no relationship between molecular conformation and packing motif variations has been found.