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

Abstract

Four Cu(II) complexes with 4- N-(2′-pyridylimine)benzoic acid ( HL), [Cu(HL) 2] · (ClO 4) 2 ( 1), [Cu(HL) 2(SO 4)] · 3H 2O ( 2), [Cu 2(L) 2Cl 2] n · 3H 2O ( 3), and [Cu 4(L) 2(HL) 2Cl 4] · (CH 3OH) 2 · (ClO 4) 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 pyridine- N 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 SO 4 2 - for ( 2). Complex ( 3) consists of a two-dimensional Cu(II) layer formed by deprotonated HL ligand linking four-membered Cu 2Cl 2 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.