PREPARATION AND CHEMICAL STUDIES ON TC(III) COMPLEXES CONTAINING POLYAMINOCARBOXYLIC ACIDS

Tc(III)-edta (edta = ethylenediaminetetraacetate), Tc(III)-dtpa (dtpa = diethylenetriaminepentaacetate) and Tc(III)-mebrofenin (mebrofenin = 3-bromo-2,4,6-trimethylacetanilideiminodiacetate) complexes were prep ared by ligand substitution reactions on hexakis(thiourea)technetium(I II) cation with the polycarboxylates. By a combination of different te chniques (UV-Vis, IR and H-1-NMR spectroscopy, Tc elemental analyses a nd cerimetric titrations) it was concluded that 1:1 complexes are form ed with edta and dtpa while mebrofenin adopts a 2:1 (ligand to metal) stoichiometry. Complementary, molecular mechanics calculations were pe rformed to analyze the spatial arrangement of the molecules. The stabi lity of the Tc(III) complexes was studied in aqueous solution by paper chromatography, paper electrophoresis and cyclic voltammetry. The che lates are rather stable, in particular when compared with the precurso r.