Polynuclear copper(II) complexes bridged by polycarboxylates of aromatic and N-heterocyclic compounds

Two categories of polynuclear Cu(II) complexes bridged by multicarboxylate compounds 2,5-pyridine dicarboxylic acid (H2Py2,5-dc), 2,4-pyridine dicarboxylic acid (H2Py2,4-dc), 2,3-pyrazine dicarboxylic acid (H2Pyaz2,3-dc) and terephthalic acid (H2tp) have been isolated with the tripod N4-donor ligands tris(2-pyridylmethyl)amine (TPA) and tris(2-isopropyl-2-aminoethyl)amine (iptren). The trinuclear bridged-carboxylato species were obtained with TPA: [(TPA)Cu-(μ2-Py2,4-dc)2Cu(H2O)2-Cu(TPA)](ClO4)2·2H2O (1), [Cu(TPA)-Cu(μ2-Py2,5dc)2-Cu(TPA)](ClO4)2 (2) and [(TPA)Cu-(μ2-Pyaz2,3-dc)2Cu(ClO4)2-Cu(TPA)][Cu(TPA)(H2O)]2(ClO4)4·4H2O (3), and the dinuclear species [Cu2(iptren)2(tp)](ClO4)2 (4) and [Cu2(iptren)2(Pyaz2,5-dc)](ClO4)2·H2O (5) with iptren. The synthesized complexes were characterized by elemental microanalyses, conductivity measurements, IR and UV-Vis spectroscopic techniques as well as by single crystal X-ray crystallography. The nature of polycarboxylate compounds used and the coligands skeletal structure play crucial role in adopting certain carboxylate-bonding mode and the nuclearity of the coordination product.