Di- and tetranuclear copper(II) complexes of a novel binucleating tetrathioether-tetrathiol ligand

A novel bi-tetradentate polythioether ligand, 6,6-methylene-bis(5-mercapto- 3-thiahexyl)-4,8-dithiaundecane-1,11-dithiol (H4L) was synthesized, and its di- and tetranuclear copper(II) complexes were prepared, and characterized by elemental analyses, magnetic moments, H-1-n.m.r., i.r., and Uv/vis spec tra. The i.r. data show that the ligand acts in a tetradentate manner and c oordinates via one S atom of the thioether and thiol groups. The geometry o f the metal chelates is discussed with the help of magnetic and spectroscop ic measurements. The elemental analyses, stoichiometry, and spectroscopic d ata of the complexes indicate that the copper(II) ions are coordinated to t he bi-dianion of the ligand. The function of the thiol ligand is to release protons to form copper(II) complexes, (Cu2L).