[Tc(OH2)(CO)3(PPh3)2]+: A Synthon for Tc(I) Complexes and Its Reactions with Neutral Ligands

A scalable synthesis of the novel and highly reactive [Tc(OH2)(CO)(3)(PPh3)(2)](+) cation is described. The ligand-exchange chemistry of this compound with neutral ligands coordinating through C, N, O, S, Se, and Te has been explored systematically. The complexes either retain the original mer-trans tricarbonyl core under exclusive exchange of the aqua ligand or form dicarbonyl complexes by thermal decarbonylation. Ligand exchange reactions starting from [ Tc(OH2)(CO)(3)(PPh3)(2)](+) proceed under mild conditions and are generally almost quantitative. Some of the formed complexes are remarkably stable and inert, while others provide products with one labile ligand for further reactions. The derived complexes of the type [Tc(L)-(CO) (3)(PPh3)(2)](+) and [Tc(L)(2)(CO)(2)(PPh3)(2)](+) represent an interesting opportunity for the development of Tc-99m complexes with potential use in radiopharmacy. The ready displacement of the aqua ligand highlights the synthetic value of [Tc(OH2)(CO)(3)(PPh3)(2)](+) as a reactive entry point for further studies in the little explored field of the organometallic chemistry of technetium.

Automated summary

A new and highly reactive [Tc(OH2)(CO)(3)(PPh3)(2)](+) cation was successfully synthesized, and its ligand exchange reactions with various neutral ligands were systematically studied. The resultant complexes exhibited different levels of stability and reactivity, offering interesting possibilities for the development of Tc-99m complexes. The ready displacement of the aqua ligand highlights the synthetic value of [Tc(OH2)(CO)(3)(PPh3)(2)](+) as a reactive entry point for further studies in the field of organometallic chemistry of technetium.