Ammonium Pertechnetate in Mixtures of Trifluoromethanesulfonic Acid and Trifluoromethanesulfonic Anhydride

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH4)(2)[TcO(OTf)(5)]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO3(OTf)], and intermediate Tc-VI species. Tc-99 nuclear magnetic resonance (NMR) has been used to study the Tc-VII compound and electron paramagnetic resonance (EPR), Tc-99 NMR and X-ray absorption near-edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH4)(2)[TcO(OTf)(5)] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH4)(4)[{TcO(TcO4)(4)}(4)] .10 H2O. Single-crystal X-ray crystallography was used to determine the solid-state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species