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

In this study, a new monoclinic polymorph (space group 2/) of 2,2'-methyl-enebis(isoindoline-1,3-dione), CHNO, is reported and compared to the previously reported triclinic polymorph (space group ). Similarly, both polymorphs consist of a unique mol-ecule in the asymmetric unit (' = 1). The mol-ecular conformations of the two polymorphs are very similar, as shown by the r.

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, CHNO·0.5HO, comprises two 2-{[(4-iminiumyl-3-methyl-1,4-di-hydro-pyridin-1-yl)meth-yl]carbamo-yl}benzoate zwitterions ( and ) and a water mol-ecule. The dihedral angles between the pyridine and phenyl rings in the zwitterions are 53.