1Department of Chemistry, University of Arak, P.O. Box 37156 Arak, I.R. IRAN
2Department of Chemistry, University of Texas at Austin, U.S.A
The synthesis and characterization of some new binuclear copper (II) complexes, based on the use of large, pyrole-containing macrocycles, the so called "expanded porphyrins", [Cu2(macrocycle)]+4 is described. Electron Spin Resonance (ESR) studies indicate a weak "half-field line", which is characteristic of the Cu(II)-Cu(II) dimer, is observed at about 1600G. The observation of this band strongly suggests that the hyperfine structure arises from a spin triplet species.