Abstract A series of heterocyclic ligand of copper (II) complexes have been synthesized by the reaction of copper (II) acetate with 5-(4′-derivatives phenylazo)-2-thioxothiazolidin-4- one (HL n) yields 1: 1 and 1: 2 (M: L) complexes depending on the reaction conditions. The elemental analysis, spectral (IR and ESR), conductance, magnetic measurements, and thermogravimetric analysis (TGA) are used to characterize the isolated complexes. It is ...