Synthesis, crystal structure, spectroscopy and magnetic properties of a dinuclear CuII complex with 3,5-bis(2-pyridyl)pyrazole bridging ligand

A dinuclear CuII complex [Cu2(bpp)2(H2O)2](ClO4)2 (1) with 3,5-bis(2-pyridyl)pyrazole (Hbpp), has been synthesized and characterized by elemental analyses, thermal analysis, conductance, UV-vis and IR spectra. The crystal structure of 1, determined by X-ray diffraction technique, reveals that two centrosymmetric CuII centers are bridged by a pair of tetradentate anionic bpp ligands, adopting a square-pyramidal environment with the water ligand occupying the axial site. An interesting feature of this structure is the formation of a two-dimensional supramolecular network through O-H⋯O hydrogen bonds between the water moieties of the cationic [Cu2(bpp)2(H2O)2]2+ subunits and perchlorate anions. The magnetic properties of 1 have been investigated by variable-temperature magnetic susceptibility and EPR measurements. Very strong antiferromagnetic interaction between the CuII centers (with H=−JS1S2, J=−368.3 cm−1) has been observed, and the magneto-structural correlations was analyzed.