Synthesis and Characterisation of [Re(CO) 3 (SS)(P)] Complexes: A [2+1] Concept for 99m Tc‐ and 188 Re‐Radiopharmaceutical Applications

A new (SS)(P) coordination set based on the concurrent use of a dithiocarbamate and a functionalised phosphane is reported. The (SS)(P) fashion is achieved by applying the [2+1] mixed‐ligand concept and makes it possible to obtain stable rhenium tricarbonyl complexes without employing tripodal bifunctional chelating agents (BFCAs). The coordination chemistry of the simple sodium N , N ‐dimethyldithiocarbamate and new functionalised phosphanes L1 – L3 [ L1 = Ph 2 PCH 2 CH 2 C(O)OCH 3 , L2 = Ph 2 PCH 2 CH 2 C(O)NHCH 2 C(O)OCH 3 , L3 = Ph 2 PCH 2 CH 2 C(O)NHCH 2 CH 2 C(O)OCH 3 ] was studied by reaction with the rhenium complex [NEt 4 ] 2 [ fac ‐Re(CO 3 )Br 3 ]. The rhenium tricarbonyl core was found to be stabilised by the SS chelation of dithiocarbamate and by the P coordination of the phosphane. Two synthetic pathways leading to the complexes [ fac ‐Re(CO) 3 (L)(MDTC)] (L = L1 , L2 , L3 ; MDTC = N , N ‐dimethyldithiocarbamate) are described. The structural characterisation of the isolated complexes by spectroscopic methods is reported, including X‐ray crystallographic analysis for rhenium complexes with ligands L1 and L3 . The homologous Tc‐99m compounds with the same (SS)(P) coordination set were prepared at tracer level with the L2 and L3 ligands, and characterised by HPLC methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)