Crystal structure refinement for 3,5-dimethyl-1,7-diphenyl-4-(2,4,6-trinitrophenyl)-2,6-diazahepta-2,4-diene and crystal structure determination for its hydrochloride

The crystal structure of 3,5-dimethyl-1,7-diphenyl-4-(2,4,6-trinitrophenyl)-2,6-diazahepta-2,4-diene (I) has been refined by X-ray crystallography; the crystal structure of its hydrochloride, (C25H24N5O6)(+) . Cl- (II), has been determined. Crystals II are trigonal, space group P3(1)21, a = 12.110(3), c = 15.135(3) Angstrom, Z = 3. The structures of I and II were solved by direct methods and refined by full-matrix least-squares analysis. anisotropically to R = 0.065 (I) and 0.049 (II) for all 4083 (I) and 3720 (II) independent (taking into account anomalous scattering for II) measured reflections (CAD-4 automatic diffractometer, lambdaMoK(alpha)). The configuration and conformation of molecule I in crystal I differ strongly from those of canon II (with a protonated nitrogen-2 atom) in crystal II. In crystal II, cation II has a twofold symmetry axis coinciding with the 2 crystallographic axis; the Cl- anion lies on the other 2 axis. In crystal II, cations II and Cl- anions are linked by N-H...Cl- type hydrogen bonds into infinite (along the z axis) helices around the 3(1) screw axes.