Mixed-ligand complexes of technetium and rhenium with tridentate benzamidines and bidentate benzoylthioureas
Mixed-ligand complexes of technetium(V) or rhenium(V) containing tridentate N-[(dialkylamino)(thiocarbonyl)]benzamidine (H2L1) and bidentate N,N-dialkyl-N'-benzoylthiourea (HL2) ligands were formed in high yields when (NBu4)[MOCl4] (M = Tc or Re) or [ReOCl3(PPh3)2] was treated with mixtures of the proligands. Other approaches for the synthesis of the products are reactions of [MOCl(L1)] complexes with HL2 or compounds of the composition [ReOCl2(PPh3)(L2)] with H 2L1. The resulting air-stable [MO(L1)(L 2)] complexes possess potential for the development of metal-based radiopharmaceuticals. [TcO(L1)(L2)] complexes are readily reduced by PPh3 with formation of [Tc(L1)(L 2)(PPh3)]. The resulting TcIII complexes undergo two almost-reversible oxidation steps corresponding to one-electron transfer processes. © 2009 Wiley-VCH Verlag GmbH & Co, KGaA.