EPR spectroscopic study of a dinuclear copper(II) complex of tolfenamic acid

The copper(II) complex with tolfenamic acid [Cu(tolf)(2)(H2O)](2) was studied by X-band and K-band EPR spectroscopies in the temperature range from 90 to 300 K. The Cu 21 ions in dinuclear complex show a strong antiferromagnetic exchange interaction with \J\ = 292 cm(-1). The EPR spectra, which were observed for [Cu(tolf)(2)(H2O)](2), are typical powder spectra of the copper pairs. The spectra exhibit the hyperfine structure in low temperature range. The values of the spin-Hamiltonian parameters were determined on the basis of the best fit for the simulated spectra at both K-band (0.75 cm(-1)) at T= 298 K and X-band (0.3 cm(-1)) at T = 93 K as compared with the experimentally observed spectra. These values show that the local environment around the copper species is distorted tetragonal pyramid. This EPR evidence is consistent with the crystallographic data. (C) 2004 Elsevier B.V. All rights reserved.