The title compounds, μ-oxalato-κ(4) O (1),O (2):O (1'),O (2')-bis-[[4-(2-amino-eth-yl)-1H-imid-azole-κ(2) N (3),N (4)](azido-κN (1))copper(II)], [Cu2(C2O4)(N3)2(C5H9N3)2], (I), and μ-ox-al-ato-κ(4) O (1),O (2):O (1'),O (2')-bis-[[4-(2-amino-eth-yl)-1H-imidazole-κ(2) N (3),N (4)](dicyanamido-κN (1))copper(II)], [Cu2(C2O4)(C2N3)2(C5H9N3)2], (II), are two oxalate-bridged dinuclear copper complexes. Each Cu(II) ion adopts a five-coordinate square-pyramidal coordination sphere where the basal N2O2 plane is formed by two O atoms of the oxalate ligand and two N atoms of a bidentate chelating histamine mol-ecule. The apical coordination site in compound (I) is occupied by a monodentate azide anion through one of its terminal N atoms. The apical coordination site in compound (II) is occupied by a monodentate dicyanamide anion through one of its terminal N atoms. The mol-ecules in both structures are centrosymmetric. In the crystals of compounds (I) and (II), the dinuclear complexes are linked through N-H⋯X and C-H⋯X (X = N, O) hydrogen bonds where the donors are provided by the histamine ligand and the acceptor atoms are provided by the azide, dicyanamide, and oxalate ligands. In compound (I), the coordinatively unsaturated copper ions inter-act with the histamine ligand via a C-H⋯Cu inter-action. The coordinatively unsaturated copper ions in compound (II) inter-act via a weak N⋯Cu inter-action with the dicyanamide ligand of a neighboring mol-ecule. The side chain of the histamine ligand is disordered over three sets of sites in (II).
Keywords: crystal structure; dinuclear copper(II) complex; histamine ligand; hydrogen bonding; oxalate ligand.