Magnetic, electronic and electrochemical studies of mono and binuclear Cu(II) complexes using novel macrocyclic ligands

A series of new mono and binuclear copper (II) complexes [Cul]X-2 and [Cu(2)1X(2)] where 1 = L-1, L-2 and L-3 are the macrocyclic ligands. In mononuclear complexes the geometry of Cu(II) ion is distorted squareplanar and in binuclear complexes the geometry of Cu(II) is tetragonal. The synthesized complexes were characterized by spectroscopic (IR,UV-vis and ESR) techniques. Electrochemical studies of the complexes reveals that all the mononuclear Cu(II) complexes show a single quasireversible one-electron transfer reduction wave (E-pc = -0.76 to -0.84 V) and the binuclear complexes show two quasireversible one electron transfer reduction waves (E-pc(1) = -0.86 to - 1.01 V, E-pc(2) = -1.11 to -1.43 V) in cathodic region. The ESR spectra of mononuclear complexes show four lines with nuclear hyperfine splittings with the observed g(perpendicular to) values in the ranges 2.20-2.28, g(perpendicular to) = 2.01-2.06 and A(11) = 125-273. The binuclear complexes show a broad ESR spectra with g = 2.10-2.11. The room temperature magnetic moment values for the mononuclear complexes are in the range [mu(eff) = 1.70-1.72 BM] and for the binuclear complexes the range is [mu(eff) = 1.46-1.59 BM]. (c) 2004 Elsevier B.V. All rights reserved.