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.

Crystal structures of 1,4-di-aza-bicyclo-[2.2.2]octan-1-ium 4-nitro-benzoate dihydrate and 1,4-di-aza-bicyclo-[2.2.2]octane-1,4-diium bis-(4-nitro-benzoate): the influence of solvent upon the stoichiometry of the formed salt.

The 1:1 co-crystallization of 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO) with 4-nitro-benzoic acid in ethanol-water (3/1) gave the salt dihydrate C6H13N2 (+)·C7H4NO4 (-)·2H2O, (1), whereas from methanol, the salt C6H14N2 (2+)·2C7H4NO4 (-), (2), was isolated.

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.

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.

N-(4-Chloro-phen-yl)-3-nitro-pyridin-2-amine.

In the title compound, C(11)H(8)ClN(3)O(2), the presence of intra-molecular N-H⋯O and C-H⋯N inter-actions help to establish an almost planar mol-ecule [dihedral angle between the pyridine and benzene rings = 9.89 (8)° and r.m.