Despite decades of research, the reduction behavior of pertechnetate, TcO₄⁻, is not well understood and represents one of the largest knowledge gaps in the transition metal series. Conventional wisdom presumes the reduction of TcO₄⁻ in aqueous systems to predominantly follow either a rapid two electron, or three electron process to form either a Tc^V or Tc^IV species. This study for the first time demonstrates the importance of the Tc^VI species through systematic characterization by multiple spectroscopic techniques. The reduction of TcO₄⁻ was examined in a matrix of 5 M NaNO₃ at 0–2 M NaOH. Results of the cyclic voltammetric evaluation of reduction to Tc^VI, Nernstian analysis of the visible spectroelectrochemical signal, and structural spectroscopic EPR and XPS analysis of the reduction product generated by bulk electrolysis consistently support an electron transfer stoichiometry corresponding to a 1e⁻ reduction. This Tc^VI species is markedly more stable than had been previously considered, with decomposition kinetics that correspond to a half-life of 1.91 ± 0.07 days, fully 6 orders of magnitude longer than previously reported for an aqueous solution. These results reveal the importance of a Tc^VI intermediate species in high ionic strength alkaline solutions and significantly contribute to the understanding of the mechanism of TcO₄⁻ reduction and formation of low-valent Tc species.

中文翻译：

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在高离子强度碱性介质中 惊人地形成准稳定的Tc（vi）†

尽管数十年的研究，高锝酸盐的减持行为，TCO ₄ ^- ，还不是很清楚，并表示在过渡金属系列最大的知识差距之一。传统智慧假定TCO的还原₄ ^-在水性体系中，以主要遵循任一快速两个电子，或三个电子处理，以形成一个任锝^V或TC ^IV物种。这项研究首次通过多种光谱技术对Tc ^VI物种进行了系统表征，证明了其重要性。TCO的还原₄ ^-中的5M的NaNO的基质检查₃在0–2 M NaOH中。减少到锝的循环伏安评价结果^VI，可见光谱电化学信号的能斯特分析和结构分光EPR和通过本体电解所产生一贯支持对应于一个1E电子转移化学计量的还原产物的XPS分析^-还原。这种Tc ^VI物质比以前认为的要稳定得多，其分解动力学相当于1.91±0.07天的半衰期，比以前报道的水溶液要长6个数量级。这些结果揭示了Tc ^VI的重要性在高离子强度的碱性溶液中间物种和显著有助于TCO的机制的理解₄ ^-还原和形成低原子价锝物种。