Ammonium Pertechnetate in Mixtures of Trifluoromethanesulfonic Acid and Trifluoromethanesulfonic Anhydride.

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid to ammonium penta-kis(tri-fluoro-methane-sulfonato)oxido-technetate(V), (NH 4 ) 2 [TcO(OTf) 5 ]. The reaction proceeds only at exact concentrations under the exclusion of air and moisture via the formation of pertechnetyl trifluoromethanesulfonate, [TcO 3 (OTf)], and intermediate Tc(VI) species. 99 Tc nuclear magnetic resonance (NMR) has been used to study the Tc(VII) compound and electron paramagnetic resonance (EPR), 99 Tc NMR and X-ray absorption near-edge structure (XANES) experiments indicate the presence of reduced technetium species. (NH 4 ) 2 [TcO(OTf) 5 ] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH 4 ) 4 [{TcO(TcO 4 ) 4 } 4 ] ⋅ 10 H 2 O. Single crystal X-ray crystallography was used to determine the solid state structures. Ultraviolet-visible (UV-vis) absorption spectroscopy and quantum chemical calculations further confirm the identity of the species.