Rhenium-Komplexe von Sauerstoffchelatliganden: Ein Weg zu neuen Radiopharmaka?

Rhenium Complexes Stabilized by Tris-chelating Oxygen Ligands: Potential New Radiopharmaca? Ris-chelating oxygen ligands of the general formula L^? = (C₅H₄R)Co{P(O)R′R″}₃]^? (R = COOCH₃, COOH and R′ = OCH₃; R = H and R′ = O(CH₂)₅COOCH₃, O(CH₂)₅COOH; R″ = OCH₃) have been synthesized. These ligands L^? and others of the same type have been used to prepare the rhenium oxo complexes LReO₃] and LReOX₂] (X = Cl, Br, I). In order to judge their use in radioimmunotherapy the corresponding complexes containing radioactive rhenium isotopes have also been synthesized. The rhenium(VII) as well as the diamagnetic rhenium(V) complexes are stable in air in the solid state as well as in organic solvents. They hydrolyze slowly in water to yield perrhenic acid. The X-ray structures of the sodium salt Na(C₅H₄COOCH₃)Co{P(O)(OCH₃)₂}₃] and of the rhenium complex LReOBr₂] (R = H, R′ = R″ = OCH₃) have been determined. The sodium salt crystallizes in trimeric units with the composition (NaL)₃ · 3 H₂O]. Each sodium has a distorted octahedral oxygen coordination. In LReOBr₂] the ReO₄Br₂ octahedron is only slightly distorted.