Searching for a polymorph: Second crystal form of 6-amino-2-phenylsulfonylimino-1,2-dihydropyridine

Too difficult to predict? The second polymorph of the title compound, is presented. A comparison of hydrogen-bond patterns and lattice energies suggests that the previously obtained form (see picture, left) is a kinetic polymorph, while the second polymorph (right) is most likely to represent the more thermodynamically stable form. The new polymorph, however, has two symmetry-independent molecules, which rendered it beyond the limit of previous structural predictions.