EPR Study of 5-Chlorosalicylate-Cu(II)-N,N-Diethylnicotinamide Ternary Complex Systems in Frozen Water-Methanol Solutions

As a continuation of our previous study of Cu(II) ternary complexes, two new systems containing 5-chlorosalicylic acid (5-ClsalH) and different Cu(II) salts, with varying N,N-diethylnicotinamide (denia) concentrations, system III [CuSO4(aq) + 2(5-ClsalH(solv)) + xdenia(l)] and system IV [Cu(ac)(2)(aq) + 2 (5-ClsalH(solv)) + xdenia(l)], where x = 0, 2, 4, 6 and 8, were prepared. The effects of Cu(II) salts containing anions of different basicity and N-donor ligand (denia) with varying ligand-to-metal ratio (x) on the formation of resulting complexes were studied by electron paramagnetic resonance (EPR) spectroscopy in frozen water-methanol solutions. Well-resolved N-14 superhyperfine splitting lines (nonet) in the perpendicular region of the second-derivative axially symmetric Cu(II) EPR spectra indicated that for x > 4 in system III and for x >= 2 in system IV, four equivalent nitrogens could be coordinated to the central Cu(II) ions in the equatorial plane. Such information cannot be obtained by EPR spectroscopy of powder samples of the given Cu(II) complex systems. The differences between denia and ronicol containing Cu(II) complexes are discussed.