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

• Published in: Journal of molecular structure Vol. 1011; pp. 99 - 104
• Main Authors: Santos, Igor F., Guedes, Guilherme P., Mercante, Luiza A., Bernardino, Alice M.R., Vaz, Maria G.F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 14-03-2012
• Subjects: Chloride ions; copper; Copper(II) complex; Coupling (molecular); Crystal structure; Distortion; ions; Ligands; Magnetic properties; magnetism; Molecular magnetism; Molecular structure; nitrogen; Pyrazole; Synthesis; Copper(II) complex; Molecular magnetism; Pyrazole; Crystal structure
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2011.12.036

► Monomeric copper(II) complex with pyrazole derivative ligands. ► The metal ions display cis and trans conformation depending on the ligand. ► A network of intermolecular interactions stabilizes the crystal packing. ► Magnetic measurements reveal weak antiferromagnetic interactions.
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 CuCl2·2H2O using an appropriate solvent. The crystalline structures of [Cu(L1)2Cl2] (1), [Cu(L2)2Cl2] (2) and [Cu(L3)2Cl2] (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.