catena-Poly[{μ(3)-4,4',6,6'-tetra-chloro-2,2'-[butane-1,4-diylbis(nitrilo-methanyl-yl-idene)]diphenolato}{μ(2)-4,4',6,6'-tetra-chloro-2,2'-[butane-1,4-diylbis(nitrilo-methanylyl-idene)]diphenolato}dicopper(II)].

The asymmetric unit of the title compound, Cu(2)(C(18)H(14)Cl(4)N(2)O(2))(2), contains two independent Cu(II) ions which are bridged by a pair of 4,4',6,6'-tetra-chloro-2,2'-[butane-1,4-diylbis(nitrilo-methanylyl-idene)]diphenolate ligands, forming a dinuclear unit. One of the Cu(II) ions is coordinated in a distorted square-planar environment and the other is coordinated in a distorted square-pyramidal environment. The long apical Cu-O bond of the square-pyramidal coordinated Cu(II) ion is formed by a symmetry-related O atom, creating a one-dimensional polymer along [010]. In addition, short inter-molecular Cl⋯Cl distances [3.444 (2) Å] and weak π-π inter-actions [centroid-centroid distances = 3.736 (2)-3.875 (3) Å] are observed. The crystal studied was an inversion twin with a refined twin component ratio of 0.60 (1):0.40 (1).