Synthesis and Characterization of Non‐Aqueous [Tc^XM‐PW₁₁O₃₉]^n– with M = O, N: Comparing Tc^V and Tc^VI in Metal Oxide Matrices

Abstract

Technetium-99, a prevalent by-product of the nuclear fuel cycle, is a transition metal with 9 accessible oxidation states and a half-life of 2.1 × 10 5 years. 99 Tc VII has been found in the environment surrounding National Lab sites and fuel reprocessing centers, and its separation and long-term storage is complicated by its extensive redox chemistry. In our prior work we have reported the synthesis and reduction of Tc V O to Tc IV O in α 1 -and α 2 -Wells-Dawson P 2 W 17 O 61 10polyoxometalates and reported on the polyoxometalate features that promote reduc- [a]

Strategies for the Photoreduction of Tc‐99 Pertechnetate to Low‐Valent Tc by Keggin Polyoxometalates

“…This fundamental study, along with our previous reports using the α 2 ‐[P 2 W 17 O 61 ] 10– and Keggin ions for binding of Tc,, demonstrate that POMs have sites that can stabilize different Tc oxidation states and can be useful to understand the coordination chemistry of reduced Tc. Specifically, we demonstrated the different coordination geometries and sites provided by POMs dictate the Tc oxidation states (IV and V).…”

“…The individual XANES experiments are shown in Figure S10 for PW 12 A, SiW 12 A, and AlW 12 A, respectively (year 1) and in Figure S11 for PW 12 B, SiW 12 B (year 2) and PW 12 C, (sample prepared in year 1 and analyzed in year 2). In year 1, the XANES was modeled by a general Tc IV reference sample and a Tc V =OPW 11 or Tc V =OP 2 W 17 reference sample and in year 2, XANES was modeled by two Tc IV reference samples, Tc IV EDTA that is a marker for the µ‐dioxo Tc IV species, and the Tc IV (µ‐O) 2 Tc IV4+ dimer and TcO 2 · 2H 2 O. Due to these different XANES fitting parameters for the two studies, a summation of the reduced species is represented as part of Table .…”

“…Moreover, that study demonstrated the different coordination geometries and sites provided by POMs depending on the Tc oxidation states (IV and V). This type of study, wherein Tc is reduced by photoactivated POMs can report on the specific molecular coordination environment that matches the Tc oxidation state, and prior work by our lab shows that the Tc oxidation state is impacted by the coordination environment …”