Synthesis, crystal structure and magnetism of three novel copper(II) complexes with pyrazole-based ligands

In this work we present the synthesis, crystal structure and magnetic properties of three copper(II) pyrazole-based complexes. These compounds were prepared by reactions between the ligands (L1 = 5-amino-1-phenyl-1H-pyrazole-4-carbonitrile, L2 = 5-amino-1-(4'metoxiphenyl)-1H-pyrazole-4-carbonitrile and L3 = Ethyl 5-amino-1-phenyl-1H-pyrazole-4-carboxylate) and CuCl2 center dot 2H(2)O using an appropriate solvent. The crystalline structures of [Cu(L1)(2)Cl-2] (1), [Cu(L2)(2)Cl-2] (2) and (Cu(L3)(2)Cl-2] (3) showed that copper ion is coordinated by two pirazolic ligands through pyridinic nitrogen atom and two chloride ions in a distorted square-planar geometry. The magnetic measurements revealed a paramagnetic behavior for (1) and weak antiferromagnetic coupling between copper(II) ions in (2) and (3). Due to the presence of labile chloride ions in the structures, these monomeric copper(II) complexes may be used as building blocks in the synthesis of molecular magnetic compounds. (C) 2012 Elsevier B.V. All rights reserved.