The Reduction of Ammonium Pertechnetate and Chelation of Oxotechnetium(V) by 2-Benzimidazole-2-Ylethanethiol

The synthesis of these technetium radiopharmaceuticals often requires a prereduction of pertechnetate with sodium dithionite or stannous chloride prior to complex formation. We now describe the product of the reaction between pertechnetate and 2-benzimidazole-2'-ylethanethiol (Hbls). In this reaction, the ligand Hbls serves as an acid to hydrolyze oxo ligands of the pertechnetate ion, as a reducing agent for technetium (VII), and as a chelating agent for technetium (V). The product of this reaction is the cationic complex Tc V O(bls) 2 + , which was isolated as [TcO(bls) 2 ][TcO 4 ] and as [TcO(bls) 2 ] BPh 4