Synthesis, characterization and magnetic properties of copper(II) complexes with 4-N-(2′-pyridylimine)benzoic acid

Four Cu(II) complexes with 4-N-(2'-pyridylimine)benzoic acid (HL), [Cu(HL)(2)] center dot (ClO4)(2) (1), [Cu(HL)(2)(SO4)] center dot 3H(2)O (2), [Cu-2(L)(2)Cl-2](n) center dot 3H(2)O (3), and [Cu-4(L)(2)(HL)(2)Cl-4]center dot(CH3OH)(2)center dot(ClO4)(2) (4), have been synthesized and structurally characterized by X-ray crystallography. Complexes (1) and (2) both exhibit a mononuclear structure with a four-coordinated Cu(II) ion by the pyridineN and imine-N atoms of the ligands for (1) and a penta-coordinated Cu(II) ion by pyridine-N, imine-N atoms of the ligands and one oxygen atom of SO42- for (2). Complex (3) consists of a two-dimensional Cu(II) layer formed by deprotonated HL ligand linking four-membered Cu2Cl2 units. Complex (4) contains a tetranuclear Cu(II) coordination cation in which the Cu(II) ions are penta-coordinated in square pyramidal geometry by two bridging chloride atoms, two nitrogen atoms of HL ligand with undeprotonated carboxylic group, and one oxygen atom of syn,syn-carboxylato bridge. Magnetic susceptibility data show a weak ferromagnetic coupling between the Cu centers in (3) (J = 4.95 cm(-1)) and a weak antiferromagnetic interaction in (4) (J = -16.85 cm(-1)), respectively. (C) 2007 Elsevier B.V. All rights reserved.