NOVEL TECHNETIUM AND RHENIUM COMPLEXES WITH MULTIDENTATE NITROGEN ANDSULFUR DONOR LIGANDS

The structural characterization of the distorted octahedral complex Tc O(HAF)(PAC), containing the terdentate ONS2- donor Schiff base ligand HAF(2-) and the bidentate NS- donor ligand PAC(-), is reported. The ox ygen donor atom of the terdentate ligand occupies the coordination sit e trans to the Tc=O bond, with the N2S2 donors in the equatorial plane . It was previously implicated that, complexes of this type could not be formed. The complex ReOCl3(PPh(3))(HMEC), formed by the reaction of trans-ReOCl3(PPh(3))(2) with the potentially bidentate NS- donor liga nd l-2-(N-ethylamino)-1-cyclopentenedithiocarboxylate (HMEC) in aceton e, was also structurally characterized. It was found that the ligand H MEC coordinates to the rhenium(V) in an unexpected monodentate manner through the neutral thiocarbonyl sulfur atom.