Conformational dimorphism of 2,2'-methyl-enebis(isoindoline-1,3-dione).

In this study, a new monoclinic polymorph (space group C2/c) of 2,2'-methyl-enebis(isoindoline-1,3-dione), C17H10N2O4, is reported and compared to the previously reported triclinic polymorph (space group P ). Similarly, both polymorphs consist of a unique mol-ecule in the asymmetric unit (Z' = 1). The mol-ecular conformations of the two polymorphs are very similar, as shown by the r.m.s. deviation of 0.368 Š(excluding all H atoms). The inter-molecular inter-actions of both polymorphs are described along with the Hirshfeld surface analysis, and the lattice energies are calculated.

The crystal structure of zwitterionic 2-{[(4-imin-iumyl-3-methyl-1,4-di-hydro-pyridin-1-yl)meth-yl]carbamo-yl}benzoate hemihydrate.

The asymmetric unit of the title compound, C15H15N3O3·0.5H2O, comprises two 2-{[(4-iminiumyl-3-methyl-1,4-di-hydro-pyridin-1-yl)meth-yl]carbamo-yl}benzoate zwitterions (A and B) and a water mol-ecule. The dihedral angles between the pyridine and phenyl rings in the zwitterions are 53.69 (10) and 73.56 (11)° in A and B, respectively. In the crystal, mol-ecules are linked by N-H⋯O, O-H⋯O, C-H⋯O and C-H⋯π(ring) hydrogen bonds into a three-dimensional network. The crystal structure also features π-π inter-actions involving the centroids of the pyridine and phenyl rings [centroid-centroid distances = 3.5618 (12) Šin A and 3.8182 (14) Šin B].