ESR STUDY OF SOME COPPER(II)-1,4-DIHYDRAZINOPHTHALAZINE COMPOUNDS

The following copper(II) compounds [CuCl2 . DHP . H2O](2) . 2H(2)O and [CuBr2 . DHP . H2O](2) . H2O, where DHP = 1,4 dihydrazinophthalazine, were prepared and investigated by ESR spectroscopy. Powder ESR spectr a of the compounds at room temperature exhibit the absorption typical of randomly oriented triplet state (S = 1) of dimeric species having a n axial symmetry with a small rhombic distortion. The magnetic suscept ibility data showed also the presence of dimeric species characterized by an antiferromagnetic coupling with a triplet-singlet separation of J.100 cm(1). The central part of the 4.2 K spectrum is typical for th e isolated Cu2+ in a square-planar environment. Characteristic values of the ESR parameters ((parallel to) = 2.207, g perpendicular to = 2.0 56, parallel to = 190 G, a(N) = 18 G) suggest the presence of CuN4 arr angement. The solution spectra of these compounds adsorbed on HY zeoli te show the presence of various monomeric species at room temperature. Some delicate changes in the coordination polyhedra symmetry and the covalency degree of metal-ligand bonds depending on the solvent nature were evidenced.