Novel rhenium(V) nitride complexes with dithiocarbimate ligands – A synchrotron X-ray and DFT structural investigation

The application of rhenium complexes as therapeutic agents in nuclear medicine has propelled research into the chemistry of these compounds. In our effort to develop and investigate new therapeutic radiopharmaceuticals based on the complexes of rhenium we have investigated the nitride core, [ReN]²⁺. This work looks at the behavior of sulfonamide based dithiocarbimates towards the rhenium(V) nitride core. The aim here was to prepare anionic complexes with aromatic as well as fluorescent aromatic groups in the sulfonamide substituent located on the dithiocarbimate backbone. We envisaged that the polar sulfonamide and dianionic charge would confer solubility in water. Here we report the reactions of the dithiocarbimate ligands towards the rhenium(V) precursors: [ReNCl₂(PPh₃)₂] and [ReNCl₂(PMe₂Ph)₃]. These reactions proceeded with bis-substitution by the dithiocarbimate ligand, resulting in the formation of a dianionic rhenium(V) complex, of the type [ReN(S-S)₂]²⁻, where (S-S) denotes the sulfonamide-tagged dithiocarbimato unit. Spectroscopic characterization data, as well as the synchrotron X-ray diffraction structure of the metal complex with the phenyl sulfonamide backbone shed light into the structural features of this interesting class of ligands and opens up opportunities for further studies in molecular imaging and therapeutic arenas.