Formation of the Tc≡N multiple bond from the reaction of ammonium pertechnetate with S-methyl dithiocarbazate and its application to the preparation of technetium-99m radiopharmaceuticals

The reaction of pertechnetate with the S-methyl ester of dithiocarbazic acid, H2N-NR-C(=S)SCH3 (R = H or CH3), in the presence of HCl and triphenylphosphine, affords the technetium(V) nitrido complex [TcNCl2(PPh3)2] in high yield. Derivatives of S-methyl dithiocarbazate of the type R1(R2)C=N-NR3-C(=S)SCH3, where R1 = o-C6H4OH, C6H5, or CH3, R2 = H or CH3, and R3 = H or CH3, behave as sources of N3- groups, giving rise to a variety of technetium complexes containing the Tc≡N multiple bond. These reactions apply equally well to the preparation of technetium-99m radiopharmaceuticals containing the Tc≡N group, at the non-carrier-added level of nuclear medicine.