Synthesis and structure of a copper(II) tetranuclear complex of 3-(6-methyl-2-pyridyl)-5-(2-pyridyl)pyrazole ligand

The reaction of the ligand 3-(6-methyl-2-pyridyl)-5-(2-pyridyl)pyrazole (HL) with Cu(NO3)2·3H2O gives a complex of formula [Cu4L4(NO3)3](NO3), which has been characterised by elemental analyses, infrared and electronic spectroscopies and single-crystal X-ray diffraction. The molecular structure of this complex is tetranuclear. The Cu2+ ions are linked to four ligands, forming a macromolecular cyclic system. The co-ordination geometries of the Cu(II) are square pyramid. The formation of this complex implies a control of nuclearity by steric hindrance.