RHODIUM-105 COMPLEXES AS POTENTIAL RADIOTHERAPEUTIC AGENTS

Rhodium-105 complexes have been investigated for their suitability as the basis of potential bifunctional chelating agents for therapeutic r adiopharmaceuticals. Rhodium-105 is a reactor-produced therapeutic rad ionuclide that is available in high specific activity. The chemistry a nd biology of several six-coordinate Rh-(III) complexes of the general form [RhCl2L](+), where L is a tetradentate ligand containing at leas t three thioethers donor atoms, is discussed. The backbone chain lengt h of the acyclic or macrocyclic ligand determines the geometry about t he Rh-(III) centre (cis vs. trans), with the larger ligands preferenti ally forming trans-dichloro complexes. The stability of all of the Rh- 105 complexes is very high (>5 days) and the biological clearance prop erties of the complexes are consistent with their relative lipophilici ties.