Résumé
Over five decades ago the formation of plutonium peroxo complexes were describedthrough the addition of hydrogen peroxide to acidic Pu(IV) solutions leads to the creation ofcolored complexes, transitioning from brown to red as the concentration of H2O2 increaseswith various proposed structures[1]. Excessive amounts of H2O2 relative to Pu(IV) result inthe formation of green precipitates, which have been used as precursors for PuO2 or inwaste management processes[2]. Today the only resolved structure for a Pu peroxocompound in the literature involves a dimeric peroxo carbonato compound with bridgingµ2,η2-O2 ligands[3]. In this structure, the ten-coordinated Pu atoms are bonded to oxygenatoms from side-on coordinated peroxide ligands and oxygen atoms from bidentatecarbonato ligands. In this study we synthetized a new peroxo based tetravalent plutoniumcomplex solution by adding Pu(IV) in highly concentrated H2O2 solutions (n(H2O2)/n(Pu)ratio > 10) with low Pu(IV) concentrations ([Pu] < 10 mM) and a pH of 1-2, a stable greencomplex solution forms without any precipitate. The resulting solution displayed uniquecharacteristics, with sharp absorption bands at 455 nm and 820 nm and a larger band inthe 654-660 nm range (Fig.1). The dried solid results in a green precipitate with anabsorption spectra identical to those of the stable green complex in solution. In conclusion,the study highlights the discovery of a soluble green peroxo complex based on Pu(IV),which bears similarities to a green solid compound found during the Manhattan Project.This discovery sheds new light on a chapter of science deeply intertwined with the historyof nuclear research.