PREPARATION OF TC-99M-THIOUREA COMPLEX AS A PRECURSOR FOR TC(III) LABELED COMPOUNDS

Ligand exchange is one of the possible synthetic routes to obtain Tc-9 9m coordination compounds. However, the success of this route depends on the availability of good precursors. The objective of this work is the preparation of the complex [Tc-99m(tu)(6)](3+) (tu = thiourea), as a potential precursor for Tc-99m(III) coordination compounds. The pre paration was successfully performed in acidic conditions, the excess o f tu serving as reducing agent. At pH values higher than 3, the compou nd becomes unstable and on addition of polydentate ligands new Tc(III) complexes are formed. With edta, the complex Tc-99m(III)-edta was obt ained in high yield.