Ligand exchange reactions between copper(II) or nickel(II) chelates of different unsaturated sulfur- and selenium-containing ligands were investigated. A series of mixed ligand complexes with maleonitriledithiolate and 1,1-disubstituted ethylene-2,2-dichalcogenolates or dithiocarbimates, respectively, could be synthesized and characterized by analytical data, voltammetric and conductivity measurements