New mixed ligand Co(II), Ni(II), Cu(II), Zn(II). Cd(II) and Hg(II) complexes of saccharin (sac) with ethanolamine (ea) and diethanolamine (dea) were synthesized and characterized by elemental analyses, magnetic moments, UV-Vis and IR spectra. The Co(II)-ea, Co(II)-dea and Cu(Il)-dea complexes are dimeric, while all the other complexes of ea and dea are mononuclear. The crystal structures of [Zn(ea)(2)(sac)(2)] and [Cu-2(mu -dea)=(sac)(2)] complexes were determined by single crystal X-ray diffraction. In the Zn(II) complex, the Zn(II) ion sits on a center of symmetry and is octahedrally coordinated by two bidentate ea (N, O) and two monodentate sac (N) ligands. The centrosymmetric binuclear Cu(II) complex contains two strongly distorted square-planarly coordinated Ctl(II) ions bridged by two alkoxo groups of the deprotonated dea. The dea ligand also coordinates to the Cu(II) ions through its nitrogen, while the other ethanolic group does not involve in coordination. The saccharinate anion coordinates to the Cu(II) ion with its nitrogen. Thermal behavior of the complexes was studied using DTA and TG in nitrogen atmosphere. Endothermic degradation of the ea and dea ligands occurs in the first stages of decomposition and the sac anions decompose at higher temperatures to give corresponding metal oxides or metals. (C) 2001 Elsevier Science Ltd. All rights reserved.