catena-Poly[[bis(quinoxaline-κN)-cobalt(II)]-di-μ-dicyanamido-κ2N1:N5] and catena-poly[[bis(quinoxaline-κN)copper(II)]-di-μ-dicyanamido-κ2N1:N5]

Two new complexes, [Co(C2N3)(2)(C8H6N2)(2)], ( I), and [Cu(C2N3)(2)(C8H6N2)(2)], ( II), are reported. They are essentially isomorphous. Complex ( I) displays distorted octahedral geometry, with the Co atom coordinated by four dicyanamide nitrile N atoms [Co - N = 2.098 ( 3) and 2.104 ( 3) Angstrom] in the basal plane, along with two monodentate quinoxaline N atoms [Co - N = 2.257 (2) Angstrom] in the apical positions. In complex ( II), the Cu atom is surrounded by four dicyanamide nitrile N atoms [Cu - N = 2.003 (3) and 2.005 (3) Angstrom] in the equatorial plane and two monodentate quinoxaline N atoms [ Cu - N = 2.479 (3) Angstrom] in the axial sites, to form a distorted tetragonal - bipyramidal geometry. The metal atoms reside on twofold axes of rotation. Neighbouring metal atoms are connected via double dicyanamide bridges to form one-dimensional infinite chains. Adjacent chains are then linked by pi-pi stacking interactions of the quinoxaline molecules, resulting in the formation of a three-dimensional structure.