Structural characterization of some oxalato-bridged copper(II) and nickel(II) complexes

A new series of dinuclear oxalato-bridged copper(II) and nickel(II) complexes derived from tridentate amines: [Cu2(Medpt)2(μ-C2O4)](ClO4)2 (1), [Cu2(pmedien)2(μ-C2O4)](ClO4)2 (2), [Cu2(DPA)2(μ-C2O4)(ClO4)2]·2H2O (3), and [Ni2(Et2dien)2(μ-C2O4)(H2O)2](ClO4)2·2H2O (4) (C2O42− = oxalate dianion, Medpt = 3,3′-diamino-N-methyldipropylmine, pmedien = N,N,N′,N′′,N′′-pentamethyldiethylenetriamine, DPA = di(2-pyridylmethyl)amine and Et2dien = N,N-diethyldiethylenetriamine) were synthesized and structurally characterized by X-ray crystallography. The spectral and structural characterizations of these complexes are reported. In this series, structures consist of the C2O42− bridging the two M(II) centers in a bis-bidentate bonding mode. The Cu2+ centers are coordinated to the tridentate amines Medpt or pmedien in distorted SP geometry in 1 and 2, respectively, with the ClO4− groups as counter ions. In the other two complexes, distorted octahedral geometries were achieved by the three nitrogen donors of the DPA and by an oxygen atom from coordinated perchlorate ion in 3 and by the Et2dien and one water molecule in 4.