Rhenium complexes of bidentate, bis-bidentate and tridentate N-heterocyclic carbene ligands

摘要: A series of eight Rhenium(I)-N-heterocyclic carbene (NHC) complexes the general form [ReCl(CO)3(C^C)] (where C^C is a bis(NHC) bidentate ligand), [ReCl(CO)3(C^C)]2 bis-bidentate tetra-NHC ligand) and [Re(CO)3(C^N^C)]+[X]− C^N^C bis(NHC)-amine ligand counter ion X either ReO4− or PF6−) have been synthesised using Ag2O transmetallation protocol. The novel precursor imidazolium salts Re(I) were characterized by elemental analysis, 1H 13C NMR spectroscopy molecular structures for two salt six determined single crystal X-ray diffraction. These NHC systems are interest possible applications in development Tc-99m Re-186/188 radiopharmaceuticals as such stability [Re(CO)3(C^N^C)][ReO4] evaluated challenge experiments metal binding amino acids L-histidine L-cysteine. studies showed that former was unstable, with chloride being replaced cysteine histidine, while no evidence transchelation observed latter suggesting ligands this type may be suitable biological applications.