Rhenium(I) and technetium(I) fac-M(NSO)(CO)3 (M = Re, 99mTc) tricarbonyl complexes, with a tridentate NSO bifunctional agent: Synthesis, structural characterization, and radiochemistry

The synthesis and structural characterization of the neutral rhenium complex fac-[Re(NSO)(CO)3], Re-1, where (NSO) is a tridentate bifunctional chelating agent, 3-(carboxymethylthio)-3-(1H-imidazol-4-yl)propanoic acid (1), is presented. The complex crystallized from methanol–water and its structure was assigned by IR and 1H, 13C NMR spectroscopies and X-ray crystallography. Furthermore, the analogous technetium complex fac-[99mTc(NSO)(CO)3], 99mTc-1, was synthesized in high yield by reacting ligand 1 with the fac-[99mTc(OH2)3(CO)3]+ precursor for 30 min at 85 °C. The tracer complex was found to be more than 95% stable in the L-histidine challenge experiment. Our data indicate that the bifunctional NSO chelating agent 1 can be successfully applied for the development of potential 99mTc-radiopharmaceuticals.

Graphical abstractThe synthesis and characterization of the fac-[Μ(NSO)(CO)3] complexes, where M = Re or 99mTc and NSO is a tridentate bifunctional chelating agent, 3-(carboxymethylthio)-3-(1H-imidazol-4-yl)propanoic acid are presented. The bifunctional NSO chelating agent could be applied for the development of target-specific technetium and rhenium radiopharmaceuticals.Figure optionsDownload full-size imageDownload as PowerPoint slide