The preparation of technetium oxyfluorides and their characterization by 99Tc, 17O and 19F NMR spectroscopy

Abstract

Relatively little is known about the chemistry of technetium, especially in its highest oxidation state. At the same time, 99Tc (I=9/2, Q=−0.19 × 10−24cm 2) is one of the more sensitive NMR nuclei (sensitivity relative to the proton is 0.275 at 100% abundance). Pertechnetate, TcO 4 −, the standard for 99Tc NMR spectroscopy, also displays primary isotopic shifts for 17O- and 18O-enriched samples. Technetium-99 NMR has proven an invaluable structural probe in the study of Tc(VII) oxyfluorides. Noble gas fluorides (KrF 2 and XeF 6) have been used to synthesize novel Tc(VII) species from solutions of TcO 3F in anhydrous HF, i.e. Tc 2O 5F 4 and TcO 2F 3. Pertechnetyl fluoride has also been prepared and its fluoride ion donor properties studied in HF solution. Solid TcO 3 +AsF 6 − has been isolated from these solutions and characterized. In addition to 99Tc NMR, compounds have also been studied by 19F and 17O (enriched) NMR spectroscopy.