4,5-Diaminobenzene-1,2-dicarbonitrile

ConnCensus Vol. 45 No. 12

2,5-Diamino­thio­phene-3,4-dicarbonitrile

In the title compound, C(6)H(4)N(4)S, the planar mol-ecule lies across a crystallographic mirror plane. In the crystal, the mol-ecules form centrosymmetric dimers through cyclic amino N-H⋯N hydrogen-bonding associations with cyano N-atom acceptors [graph set R(2) (2)(12)] and these dimers are extended through amine-cyano N-H⋯N associations into a three-dimensional network.

4,5-Diamino­benzene-1,2-dicarbonitrile

The mol-ecular skeleton of the title mol-ecule, C(8)H(6)N(4), is essentially planar [maximum deviation from the mean plane of 0.037 (2) Å]. All N atoms are involved in the formation of inter-molecular N-H⋯N hydrogen bonds. The crystal packing exhibits also dipole-dipole inter-actions between the cyano groups of neighbouring mol-ecules [C⋯C 3.473 (2) Å].

2,6-Dichloro­pyridine-3,5-dicarbonitrile

In the crystal, essentially planar (r.m.s. deviation = 0.003 Å) mol-ecules of the title compound, C(7)HCl(2)N(3), form chains along the b axis by means of C-H⋯N inter-actions. These chains are further linked into layers parallel to the ab plane by C-Cl⋯N inter-actions.

5,6-Dimethyl­pyrazine-2,3-dicarbonitrile

The asymmetric unit of the title compound, C(8)H(6)N(4), contains two almost planar independent mol-ecules (r.m.s. deviations = 0.026 and 0.030 Å). The crystal studied was a non-merohedral twin with the components in a 0.513 (2):0.487 (2) ratio.