Synthesis and structural characterization of novel neutral fac-M(CO)3(NSO) complexes (M = Re, 99mTc) with N-acetylcysteine derivatives as tridentate NSO ligands

The reaction of [NEt4]2[Re(CO)3Br3] with equimolar amount of a tridentate NSO ligand in methanol leads to the formation of neutral tricarbonyl rhenium(I) complexes of the general formula Re(CO)3(NSO), where the NSO ligand is o-C5H4N-CH2CH2-S-CH2CH(NHCOCH3)COOH (L1H), complex 1 or o-C5H4N-CH2CH2-S-C(CH3)2CH(NHCOCH3)COOH (L2H), complex 2. Both complexes have been characterized by elemental analysis and spectroscopic methods, while complex 2 has also been characterized by X-rays analysis. At technetium-99m level, the corresponding fac-[99mTc(CO)3(NSO)] complexes 3 and 4, were obtained in high yield by reacting ligands L1H or L2H with the fac-[99mTc(CO)3(H2O)3]+ precursor in water. Their structure was established by chromatographic comparison to the prototype rhenium complex using high-performance liquid chromatographic techniques.

Graphical abstractTwo N-acetylcysteine derivative ligands (NSO) and their stable neutral complexes with the fac-[M(CO)3(H2O)3]+ (M = Re or 99mTc) synthons are prepared and fully characterized. These NSO tridentate ligands are promising model compounds for the development of target-specific technetium and rhenium radiopharmaceuticals.Figure optionsDownload full-size imageDownload as PowerPoint slide