Two novel bis-azomethines derived from quinoxaline-2-carbaldehyde.

The Schiff base compounds N,N'-bis[(E)-quinoxalin-2-ylmethylidene]propane-1,3-diamine, C(21)H(18)N(6), (I), and N,N'-bis[(E)-quinoxalin-2-ylmethylidene]butane-1,4-diamine, C(22)H(20)N(6), (II), crystallize in the monoclinic crystal system. These molecules have crystallographically imposed symmetry. Compound (I) is located on a crystallographic twofold axis and (II) is located on an inversion centre.

N-[(E)-Quinoxalin-2-ylmethyl-idene]-1H-indazol-5-amine.

In the title mol-ecule, C(16)H(11)N(5), the mean planes of the quinoxaline and indazole fragments form a dihedral angle of 10.62 (5)°. In the crystal, weak inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into zigzag chains extending in the [001] direction.

(Z)-2-Amino-3-[(E)-benzyl-ideneamino]but-2-enedinitrile.

The asymmetric unit of the title compound, C(11)H(8)N(4), contains two independent mol-ecules. In the crystal structure, inter-molecular N-H⋯N hydrogen bonds link mol-ecules into ribbons extended in the [100] direction.

N,N'-Bis[(E)-quinoxalin-2-ylmethyl-idene]-ethane-1,2-diamine.

In the mol-ecule of the title compound, C(20)H(16)N(6), the central C-C bond lies on a crystallographic inversion centre. The quinoxalidine ring is nearly planar, with a maximum deviation of 0.021 (2) Å from the mean plane.