COPPER(II)-THIOLATE COMPLEXES WITH NOVEL TRIPODAL-LIKE AND TETRAPODAL-LIKE BENZIMIDAZOLES

The tripodal copper(II) thiolate complexes Cu(L1)(Cl). 2H(2)O and Cu(L 1)(mim)(Cl) [H(L1) = -(2-mercaptoethyl)-N,N-bis(pyrid-2'-ylmethyl)amin e and mim = N-methylimidazole] have been isolated. Both contain monome ric copper(II) and display two ligand field bands and axial cryogenic e.p.r. spectra, suggesting a square-based geometry. A copper(II) thiol ate complex Cu(L2)(ClI). H2O [H(L2) = -tris(benzimidazol-2'-ylmethyl)- 1,2-ethanediamine] with a CuN5S chromophore has been also isolated. It exhibits only one ligand field band and an axial cryogenic e.p.r. spe ctrum, consistent with a distorted tetragonal coordination geometry. A ll the thiolates display intense S- --> Cu-II charge transfer bands in the u.v. region, suggesting equatorial thiolate coordination. All of the complexes exhibit irreversible electrochemical behaviour.