Systematic Evolution from Uranyl(VI) Phosphites to Uranium(IV) Phosphates

Villa, Eric M.; Marr, Connor J.; Jouffret, Laurent; Alekseev, Evgeny V.; Depmeier, Wulf; Albrecht‐Schmitt, Thomas E.

doi:10.1021/ic3000735

Cited by 44 publications

(60 citation statements)

References 55 publications

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“…Lastly, if these reaction conditions are repeated and the reaction is heated for longer than two days, the only product that was isolated was a cesium uranium(IV) phosphate structure, Cs[U(PO4)(HPO4)x(HPO3)1−x], which has been reported previously [16]. This structure represents the complete transition from uranyl phosphite observed in (1) to the uranyl mixed phosphite-phosphate observed in (2) to a completely redox reacted uranium(IV) phosphate.…”

Section: [(H 2 Pz)cs][(uo 2 ) 2 (Hpo 3 ) 2 (Po 4 )]supporting

confidence: 55%

“…(Please note images (c)-(h) are adapted from their original publication. (c) and (d) adapted with permission from Villa et al [16]. (e) adapted with permission from Villa et al [18].…”

Section: Methodsmentioning

confidence: 99%

“…Here the phosphite anion stabilized the lower oxidation states of uranium, neptunium, and plutonium with an eye towards potential waste storage media and the exploration of periodic trends. From here, we expanded to study the in-situ redox chemistry that occurs within different uranium-phosphite systems by varying reaction times and pHs to isolate compounds with various oxidation states of U and P [16][17][18]. In these studies, uranyl phosphite compounds were formed at short reaction times (a few hours) with the addition of carbonate salts.…”

Section: Introductionmentioning

confidence: 99%

“…A table of the known uranyl phosphite compounds with different mono-and di-valent cations[16,18,22,56]. K 2 [(UO 2 ) 2 (HPO 3 ) 3 ]•2H 2 O BaUPO 3 ), and Compound(1).…”

mentioning

confidence: 99%

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New Uranyl Open Framework and Sheet Compounds Formed via In-Situ Protonation of Piperazine by Phosphorous Acid

2018

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Two new uranyl compounds were hydrothermally synthesized employing piperazine as an organic templating agent. The piperazine was protonated in-situ by phosphorous acid, forming the piperazinium dication featured in these compounds. The two new structures presented here are a uranyl phosphite 2D sheet and a 3D uranyl mixed phosphite–phosphate network with cation occupied channels. Both included strong hydrogen bonding from the piperazinium cation to the uranyl phosphite or mixed phosphite–phosphate network. These two structures can be reliably formed through careful control of pH of the starting solution and the reaction duration. The piperazinium uranyl phosphite compound was the latest in a family of uranyl phosphites, and demonstrates the structural versatility of this combination. The mixed phosphite–phosphate compound builds on hydrothermal redox chemistry, illustrating the variety of compounds that can be isolated by exploiting in-situ redox processes to elucidate new uranium structure types.

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Section: [(H 2 Pz)cs][(uo 2 ) 2 (Hpo 3 ) 2 (Po 4 )]supporting

confidence: 55%

“…(Please note images (c)-(h) are adapted from their original publication. (c) and (d) adapted with permission from Villa et al [16]. (e) adapted with permission from Villa et al [18].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…A table of the known uranyl phosphite compounds with different mono-and di-valent cations[16,18,22,56]. K 2 [(UO 2 ) 2 (HPO 3 ) 3 ]•2H 2 O BaUPO 3 ), and Compound(1).…”

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confidence: 99%

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New Uranyl Open Framework and Sheet Compounds Formed via In-Situ Protonation of Piperazine by Phosphorous Acid

2018

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“…19,20 As it is well-known, synthesis conditions do have a strong influence on phase formation in actinide chemistry. [21][22][23] For instance, pressure is a very important factor in natural as well as in synthetic systems. A major effect of pressure is the reduction of the molar volume (−ΔV), which in turn could lead to a compression of the electron shells of the atoms and can therefore lead to changes in coordination environments, to the formation of new chemical bonds and hence to phase transitions.…”

Section: Introductionmentioning

confidence: 99%

Influence of extreme conditions on the formation and structures of caesium uranium(vi) arsenates

Kegler

Klepov³

et al. 2015

Dalton Trans.

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Four new uranyl arsenates, Cs2[(UO2)(As2O7)] (1), α-Cs[(UO2)(HAs2O7)] (2), β-Cs[(UO2)(HAs2O7)] (3), Cs[(UO2)(HAs2O7)]·0.17H2O (4), were synthesized by high-temperature/high pressure (HT/HP) reactions at 900 °C and 3 GPa. These phases were subsequently characterised structurally as well as chemically. We demonstrated that compound 1 can also be obtained at ambient pressure. Compounds 1, 2, and 4 are based on two-dimensional (2D) anionic layers with two different topological types. The layers possess a similar composition, [(UO2)(As2O7)](2-) in 1 and [(UO2)(HAs2O7)](-) in 2 and 4. However, the presence of hydrogen in 2 and 4 leads to a change in coordination modes of the pyroarsenate groups. There are additional 0.17 H2O molecules per formula unit in 4, which cause slight distortions of the layers in 4. All these layers can be simplified to a common net, which is typical of autunite-like layered compounds. Compound 3 is a polymorph of compound 2, but the structural arrangements in these two are significantly different. The structure of 3 is based upon a three-dimensional (3D) framework, in which UO7 is coordinated by arsenate groups in order to form uranyl anion sheets, and UO6 is located within the interlayers. Bond valance analysis proved the presence of OH(-) groups in compounds 2, 3, and 4, respectively, and water molecules in 4. The Raman analyses enabled the study of the local environments of the arsenate and the uranyl groups within the investigated phases, respectively. It turned out that the applied HT/HP synthesis method strongly affects the crystal chemistry as well as the observed structural features of all obtained compounds.

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Ligand‐Supported Facile Conversion of Uranyl(VI) into Uranium(IV) in Organic and Aqueous Media

et al. 2020

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Reduction of uranyl(VI) to U V and to U IV is important in uranium environmental migration and remediation processes. The anaerobic reduction of a uranyl U VI complex supported by a picolinate ligand in both organic and aqueous media is presented. The [U VI O 2 (dpaea)] complex is readily converted into the cis-boroxide U IV species via diborane-mediated reductive functionalization in organic media. Remarkably, in aqueous media the uranyl(VI) complex is rapidly converted, by Na 2 S 2 O 4 , a reductant relevant for chemical remediation processes, into the stable uranyl(V) analogue, which is then slowly reduced to yield a waterinsoluble trinuclear U IV oxo-hydroxo cluster. This report provides the first example of direct conversion of a uranyl(VI) compound into a well-defined molecular U IV species in aqueous conditions. 1015 Lausanne (Switzerland)

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Systematic Evolution from Uranyl(VI) Phosphites to Uranium(IV) Phosphates

Cited by 44 publications

References 55 publications

New Uranyl Open Framework and Sheet Compounds Formed via In-Situ Protonation of Piperazine by Phosphorous Acid

New Uranyl Open Framework and Sheet Compounds Formed via In-Situ Protonation of Piperazine by Phosphorous Acid

Influence of extreme conditions on the formation and structures of caesium uranium(vi) arsenates

Ligand‐Supported Facile Conversion of Uranyl(VI) into Uranium(IV) in Organic and Aqueous Media

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