Crystal structure of a new monoclinic polymorph of N-(4-methyl-phen-yl)-3-nitro-pyridin-2-amine.

The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, with Z' = 4) of the previously reported monoclinic (P21/c, with Z' = 2) form [Akhmad Aznan et al. (2010 ▶). Acta Cryst. E66, o2400]. Four independent mol-ecules comprise the asymmetric unit, which have the common features of a syn disposition of the pyridine N atom and the toluene ring, and an intra-molecular amine-nitro N-H⋯O hydrogen bond. The differences between mol-ecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6-311 g+(d,p) basis set] has the same features except that the entire mol-ecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C-H⋯O, C-H⋯π, nitro-N-O⋯π and π-π inter-actions [inter-centroid distances = 3.649 (2)-3.916 (2) Å].

N-(3-Chloro-phen-yl)-3-nitro-pyridin-2-amine.

The dihedral angle between the benzene and pyridyl rings in the title compound, C(11)H(8)ClN(3)O(2), is 22.65 (10)°, indicating a twisted mol-ecule. The amine H and nitro O atoms form a donor-acceptor pair for an intra-molecular N-H⋯O hydrogen bond so that the nitro group is almost coplanar with the pyridine ring to which it is connected [O-N-C-C torsion angle = 7.4 (3)°]. The pyridine N and Cl atoms are approximately syn. The crystal packing features C-H⋯Cl inter-actions that lead to undulating supra-molecular chains along [101]. These are connected into sheets by π-π inter-actions occurring between the benzene rings and between the pyridine rings of translationally related mol-ecules along the b axis [centroid-centroid distances = length of b axis = 3.7157 (2) Å].

4-Nitro-benzoic acid-N-(pyrimidin-2-yl)aniline (1/1).

Four independent mol-ecules comprise the asymmetric unit of the title co-crystal, C(10)H(9)N(3)·C(7)H(5)NO(4), two for each component. Small conformational differences are noted for the benzoic acid derivatives, notably in the twists of the carb-oxy-lic acid residue out of the plane of the benzene ring to which it is connected [torsion angles = 167.62 (17) and 174.54 (17)°]. In the aniline derivative, the major difference is observed in the dihedral angles formed between the CN(3) and phenyl least-squares planes [1.51 (5) and 6.25 (6)°]. Pairs of mol-ecules associate via O-H⋯N and N-H⋯O hydrogen bonds leading to eight-membered {⋯HOCO⋯HNCN} hetero-synthons. The two-mol-ecule aggregates are consolidated in the crystal structure by C-H⋯O(nitro) and π-π inter-actions [shortest centroid-centroid distance between benzene rings = 3.6242 (10) Å].