Synthesis, structure of copper(II) complexes of S-containing pentadentate ligands

Novel ligands containing a pyridine and methylsulfanyl groups, 2,6-bis[(2-methylsulfanylethylamino)methyl]pyridine (4) and 2,6-bis[(2-methylsulfanylethylamino)methyl]-4-dimethylaminopyridine (7) were prepared and the properties of their copper complexes were studied. Potentiometric titration, absorption and ESR spectral measurement, and X-ray crystallography of copper complexes of 4 and 7 were carried out. X-ray structure of [Cu4]2+ and [Cu7]2+ revealed an intermediate geometry between the regular trigonal bipyramid with two secondary amines being axial and the regular square pyramid with one of the thioethers being apical position.