2 research outputs found
Understanding the Scarcity of Thorium Peroxide Clusters
The reaction of ThÂ(NO<sub>3</sub>)<sub>4</sub>·5H<sub>2</sub>O with 3 equiv of 2,2′,6′,2″-terpyridine (terpy) in a mixture of acetonitrile and methanol results in formation of the trinuclear thorium peroxide cluster [ThÂ(O<sub>2</sub>)Â(terpy)Â(NO<sub>3</sub>)<sub>2</sub>]<sub>3</sub>. This cluster is assembled via bridging by μ–η<sup>2</sup>:η<sup>2</sup> peroxide anions between thorium centers. It decomposes upon removal from the mother liquor to yield ThÂ(terpy)Â(NO<sub>3</sub>)<sub>4</sub> and ThÂ(terpy)Â(NO<sub>3</sub>)<sub>4</sub>(EtOH). The peroxide formation appears to be radiolytic in origin and is, most likely, generated from radiolysis of water by short-lived daughters generated from <sup>232</sup>Th decay. This cluster does not form when freshly recrystallized ThÂ(NO<sub>3</sub>)<sub>4</sub>·5H<sub>2</sub>O is used as the starting material and requires an aged source of thorium. Analysis of the bonding in these clusters shows that, unlike uraniumÂ(VI) peroxide interactions, thoriumÂ(IV) complexation by peroxide is quite weak and largely ionic. This explains its much lower stability, which is more comparable to that observed in similar zirconiumÂ(IV) peroxide clusters
Characterization of Lanthanide Complexes with Bis-1,2,3-triazole-bipyridine Ligands Involved in Actinide/Lanthanide Separation
The
complexation of selected trivalent lanthanide ions with derivatives
of the tetranitrogen donor ligands 6,6′-bis-1R,1<i>H</i>-1,2,3-triazol-4-yl-2,2′-bipyridines (BTzBPs, R = alkyl or
aryl) was investigated in solid state and in solution. An anhydrous
solid [CeÂ(Bn-BTzBP)Â(NO<sub>3</sub>)<sub>3</sub>] (Bn = benzene) complex
was synthesized and characterized by single-crystal X-ray diffraction.
EuÂ(III) complexes with the 2-ethylÂ(hexyl) derivative EH-BTzBP in methanol
were studied by time-resolved fluorescence spectroscopy. Earlier studies
have identified the EH-BTzBP as a potentially useful solvent extraction
reagent for the separation of americium from lanthanide metal ions,
a challenging component of advanced nuclear fuel cycles for actinide
transmutation. To help identify species formed in the extraction process,
the influence of 2-bromohexanoic acid (identified as an essential
component of the separation system) on EuÂ(III) complexes was investigated.
Comparison with an organic phase after extraction of EuÂ(III) by EH-BTzBP
and 2-bromohexanoic acid showed that both 1:1 and 1:2 (Eu/EH-BTzBP)
complexes are involved in the extraction. UV–visible spectrophotometry
was used to compare EuÂ(III) stability constants with those of other
LnÂ(III) complexes