Condensation mechanisms of tetravalent technetium in chloride media

Abstract : The condensation mechanisms of tetravalent technetium in chloride media were studied in the pH range 0–1.5. A new dimer complex of Tc(IV) has thus been discovered, Tc2OCl104−. Spectroscopic and kinetics studies showed that the formation of this compound resulted from the condensation of TcCl5(H2O)−. An EXAFS study indicates that the dimer displays a [Tc-O-Tc]6+ structure. As the pH increases, UV-visible measurements showed a cyclization of [Tc-O-Tc]6+ into [Tc(μO)2Tc]4+ leading, in fine, to the precipitation of TcO2·x H2O. The aquation constant (Kaq) of TcCl62− into TcCl5(H2O)− and the dimerisation constant (logKdim) of TcCl5(H2O)− into Tc2OCl104− were determined to be 2.20±0.26 and 4.68±0.09, respectively.
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Submitted on : Tuesday, May 16, 2006 - 11:33:25 AM
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F. Poineau, M. Fattahi, Gilles Montavon, Bernd Grambow. Condensation mechanisms of tetravalent technetium in chloride media. Radiochimica Acta, R Oldenbourg Verlag GMBH, 2006, 94, pp.291-299. ⟨10.1524/ract.2006.94.5.291⟩. ⟨hal-00069075⟩

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