Experimental and Quantum Mechanical Characterization of an Oxygen‐Bridged Plutonium(IV) Dimer

Ray, Debmalya; Xie, Jing; White, Jacob; Sigmon, Ginger E.; Gagliardi, Laura; Hixon, Amy E.

doi:10.1002/chem.202000638

“…ratio to almost 1:1, we obtained the NiCe70-PacMan phase (triclinic space group P-1, V = 63,794 (9) Å 3 , table S1) that features the Ce13-fragment (figure 2 6)°) resembles a recently described Pu-O-Pu dimer isolated as a nitrate salt, highlighting a similarity between these f-block elements. 60 Of the [Ce70]2-dimer, one forms the Ce13-'pacman' unit with Ce70 of the layer above, and the second with the layer below. All Ce70 rings present the same core formula as above.…”

Section: Resultsmentioning

confidence: 99%

Snapshots of Ce70 Toroid Assembly from Solids and Solution

Colliard¹,

Brown²,

Fast³

et al. 2021

Preprint

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Crystallization at the solid-liquid interface is difficult to spectroscopically observe and therefore challenging to understand and ultimately control at the molecular level. The Ce70-torroid formulated [CeIV70(OH)36(O)64(SO4)60(H2O)10] 4- , part of a larger emerging family of MIV70- materials (M=Zr, U, Ce), presents such an opportunity. We have elucidated assembly mechanisms by X-ray scattering (small-angle scattering and total scattering) of solutions and solids, as well as crystallizing and identifying fragments of Ce70 by single-crystal X-ray diffraction. Fragments show evidence for templated growth (Ce5, [Ce5(O)3(SO4)12] 10- ) and modular assembly from hexamer (Ce6) building units (Ce13, [Ce13(OH)6(O)12(SO4)14(Η2Ο)14] 6- and Ce62, [Ce62(OH)30(O)58(SO4)58] 14- ). Ce62, an almost complete ring, precipitates instantaneously in the presence of ammonium cations as two torqued arcs that interlock by hydrogen boding through NH4 +, which can also be replaced by other cations, demonstrated with CeIII. Room temperature rapid assembly of both Ce70 and Ce62, respectively, by addition of Li+ and NH4 +, along with ion?exchange and redox behavior, invite exploitation of this emerging material family in environmental and energy applications.

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“…The linear unit (Ce-O-Ce angle = 179.99(6)°) resembles a recently described Pu-O-Pu dimer isolated as a nitrate salt, highlighting a similarity between these f-block elements. 60 Of the [Ce70]2-dimer, one forms the Ce13-'pacman' unit with Ce70 of the layer above, and the second with the layer below. All Ce70 rings present the same core formula as above.…”

Section: Nice70-pacman and The Ce13 Fragmentmentioning

confidence: 99%

Snapshots of Ce₇₀ Toroid Assembly from Solids and Solution

Colliard

¹

,

Brown

²

,

Fast

³

et al. 2021

Self Cite

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Crystallization at the solid-liquid interface is difficult to spectroscopically observe and therefore challenging to understand and ultimately control at the molecular level. The Ce70-torroid formulated [Ce IV 70(OH)36(O)64(SO4)60(H2O)10] 4-, part of a larger emerging family of M IV 70materials (M=Zr, U, Ce), presents such an opportunity. We have elucidated assembly mechanisms by X-ray scattering (small-angle scattering and total scattering) of solutions and solids, as well as crystallizing and identifying fragments of Ce70 by single-crystal X-ray diffraction. Fragments show evidence for templated growth (Ce5, [Ce5(O)3(SO4)12] 10-) and modular assembly from hexamer (Ce6) building units (Ce13, [Ce13(OH)6(O)12(SO4)14(Η2Ο)14] 6and Ce62, [Ce62(OH)30(O)58(SO4)58] 14-). Ce62, an almost complete ring, precipitates instantaneously in the presence of ammonium cations as two torqued arcs that interlock by hydrogen boding through NH4 + , which can also be replaced by other cations, demonstrated with Ce III . Room temperature rapid assembly of both Ce70 and Ce62, respectively, by addition of Li + and NH4 + , along with ionexchange and redox behavior, invite exploitation of this emerging material family in environmental and energy applications. Ce70, [Ce IV 70(OH)36(O)64(SO4)60] 4-, was described prior, and is also isostructural with Zr70 and U70. [49][50][51][52] Briefly, the Ce70 cluster can be viewed as ten Ce6-hexamers that alternate with ten Ce1-monomers. Four sulfates bridge each Ce6 and Ce1 along the outer rim, and four additional sulfates bridge only Ce6 units along the inner rim. Each fragment discussed later can be viewed in the same context. The Ce62, [Ce62(OH)30(O)58(SO4)58] 14-, consisting of ~90% of the ring, contains nine Ce6 and eight Ce1. Ce13, [Ce13(OH)6(O)12(SO4)14(Η2Ο)14] 6-, consists of two Ce6 and Ce1, and is approximately 20% of the ring. Ce5 [Ce5(O)3(SO4)12] 10-, resembles half of the Ce6 plus two flanking monomers. These clusters and their intrinsic relation to the Ce70, summarized in figure 1, serve as crystallographic snapshots of mechanistic pathways for ring formation.

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“…(25) Different from thorium, the diplutonium(IV) dihydroxide bridged dimer is more elusive, isolated only once, with nitrate ligands, (26) and, more recently, singly bridged via an oxo ligand also with nitrate ligands. (27) On the basis of large isolatable clusters including U38(28−30) and Np38(31) (in addition to numerous examples of hexamers, i.e., refs (5) and (32)(33)(34)(35), the polymerization of U IV and Np IV appear to be more similar to Pu IV than Th IV . Unlike Pu38, Np38 and U38 isolation required organic media that slow olationoxolation reactions.…”

Section: Introductionmentioning

confidence: 99%

Bridging the Transuranics with Uranium(IV) Sulfate Aqueous Species and Solid Phases

Colliard

¹

,

Falaise

²

,

Nyman

³

2020

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Isolating isomorphic compounds of tetravalent actinides (i.e., Th IV , U IV , Np IV , and Pu IV ) improve our understanding of the bonding behavior across the series, in addition to their relationship with tetravalent transition metals (Zr and Hf) and lanthanides (Ce). Similarities between these tetravalent metals are particularly illuminated in their hydrolysis and condensation behavior in aqueous systems, leading to polynuclear clusters typified by the hexamer [M IV 6O4(OH)4] 12+ building block. Prior studies have shown the predominance and coexistence of smaller species for Th IV (monomers, dimers, and hexamers) and larger species for U IV , Np IV , and Pu IV (including 38-mers and 70-mers). We show here that aqueous uranium(IV) sulfate also displays behavior similar to that of Th IV (and Zr IV ) in its isolated solid-phase and solution speciation. Two single-crystal X-ray structures are described: a dihydroxide-bridged dimer (U2) formulated as U2(OH)2(SO4)3(H2O)4 and a monomer-linked hexamer framework (U-U6) as (U(H2O)3.5)2U6O4(OH)4(SO4)10(H2O)9. These structures are similar to those previously described for Th IV . Moreover, cocrystallization of monomer and dimer and of dimer and monomer-hexamer phases for both Th IV (prior) and U IV (current) indicates the coexistence of these species in solution. Because it was not possible to effectively study the sulfate-rich solutions via X-ray scattering from which U2 and U-U6 crystallized, we provide a parallel solution speciation study in low sulfate conditions, as a function of the pH. Raman spectroscopy, UV-vis spectroscopy, and small-angle X-ray scattering of these show decreasing sulfate binding, increased hydrolysis, increased species size, and increased complexity, with increasing pH. This study describes a bridge across the first half the actinide series, highlighting U IV similarities to Th IV , in addition to the previously known similarities to the transuranic elements.

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Experimental and Quantum Mechanical Characterization of an Oxygen‐Bridged Plutonium(IV) Dimer

Cited by 12 publications

References 37 publications

Snapshots of Ce70 Toroid Assembly from Solids and Solution

Snapshots of Ce70 Toroid Assembly from Solids and Solution

Snapshots of Ce₇₀ Toroid Assembly from Solids and Solution

Bridging the Transuranics with Uranium(IV) Sulfate Aqueous Species and Solid Phases

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