Di-μ-chlorido-bis[(2,2′-bipyridine-5,5′-dicarboxylic acid-κ2N,N′)chloridocopper(II)] dimethylformamide tetrasolvate

In the title compound, [Cu2Cl4(C12H8N2O4)2]·4C3H7NO, which contains a chloride-bridged centrosymmetric CuII dimer, the CuII atom is in a distorted square-pyramidal 4 + 1 coordination geometry defined by the N atoms of the chelating 2,2′-bipyridine ligand, a terminal chloride and two bridging chloride ligands. Of the two independent dimethylformamide molecules, one is hydrogen bonded to a single –COOH group, while one links two adjacent –COOH groups via a strong accepted O—H...O and a weak donated C(O)—H...O hydrogen bond. Two of these last molecules and the two –COOH groups form a centrosymmetric hydrogen-bonded ring in which the CH=O and the –COOH groups by disorder adopt two alternate orientations in a 0.44:0.56 ratio. These hydrogen bonds link the CuII complex molecules and the dimethylformamide solvent molecules into infinite chains along [-111]. Slipped π–π stacking interactions between two centrosymmetric pyridine rings (centroid–centroid distance = 3.63 Å) contribute to the coherence of the structure along [0-11].