Molecular and Crystal Structure of Three Crystal Solvates of an Azaspiro[4.5]dec-7-Ene-2,9-Dione Derivative

Abstract

The molecular and crystal structure of 2-methyl-4,14-dioxo-15-(phenylamino)-1,10-dioxa-15-azadispiro[5.0.5⁷.3⁶]pentadec-2-en-5-yl 1H-imidazole-1-carboxylate (1) presented in the form of three crystal solvates with toluene (1a), water (1b), and dioxane (1c) in 1:1, 1:1, and 1:1.5 ratios, respectively, is comparatively analyzed. Pyramidalization of the nitrogen atom in the pyrrolidinone ring in the dioxane solvate is shown to change the arrangement of spiro-fused rings. The crystal-forming motifs governed by classical hydrogen bonds in these three modifications differ from each other due to the effect of solvent molecules on the formation of a 3D crystal structure. The nature of the solvent determines the 3D crystal packing: toluene molecules are located in hydrophobic channel cavities, dioxane is localized in second-type channel cavities, while water molecules (donors and acceptors in X–H⋯O hydrogen bonds) are localized in zero-dimensional voids. A comprehensive analysis of noncovalent interactions in the crystals of the three forms is performed using Hirshfeld surfaces.