Polymorphism in Solvate Crystals of Indantrione 1,2-Dioxime

Indantrione 1,2-dioxime (1) afforded crystals solvated by different species of alcohols and in different stoichiometries. Among those, three pairs of polymorphic forms, which are of the same solvent and stoichiometry, were obtained. The crystal structures of those polymorphs, formulated as alpha- and beta-1 center dot MeOH, alpha- and beta-1 center dot 1/2MeOH, and alpha- and beta-1 center dot EtOH, were elucidated along with that of 1 center dot i-PrOH. The common building block in the crystal structures is a centrosymmetric planar dimer linked by bifurcated hydrogen bonding. The dimer is further assembled through alcohol molecules to form tapelike linear chains. The difference in crystal structure between all pans of the polymorphs is principally attributed to a distinct hydrogen bonding motif between the dimer and solvated alcohol molecules. Carbonyl-carbonyl interaction is also recognized to play a role in molecular alignment in most cases; the carbonyl groups of neighboring molecules are in close contact and have an all-planar antiparallel arrangement.