Synthesis and Characterization of a Water Stable Uranyl(V) Complex

Faizova, Radmila; Scopelliti, Rosario; Chauvin, Anne‐Sophie; Mazzanti, Marinella

doi:10.1021/jacs.8b07885

Cited by 47 publications

(73 citation statements)

References 62 publications

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“…The reduction of [UO 2 (dpaea)] with Na 2 S 2 O 4 cannot be performed in acidic aqueous media (pH lower than 7) (Supporting Information, Figure S8) because the uranyl(V) [U V O 2 (dpaea)] À complex was found to disproportionate to [U VI O 2 (dpaea)] and [U IV (dpaea) 2 ] in these conditions. [10] In contrast, no disproportionation is observed in water solutions of [NaUO 2 (dpaea)] at pH 8 to 11, but the reduction of U V to U IV is increasingly slower with increasing of pH. In strongly basic conditions (pH !…”

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confidence: 99%

“…Recently, we reported [10] the synthesis and the structure of the uranyl(V) complex [K(2.2.2.cryptand)][UO 2 (dpaea)], 2 (dpaea 2À (bis(pyridyl-6-methyl-2-carboxylate)-ethylamine), which was isolated from pyridine. Complex 2 disproportionates in acidic water conditions to yield the U VI [UO 2 -(dpaea)], 1 and U IV [U(dpaea) 2 ] complexes, but it is stable in water at pH 7-11.…”

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confidence: 99%

“…This result suggests that the redox properties of [UO 2 (dpaea)] À are pH-dependent, as previously reported for uranyl(VI) carbonate or phosphate. [14] In view of the ability of the weakly reducing agent Na 2 S 2 O 4 (E red (Na 2 S 2 O 4 ) = À0.87 V (vs. Ag/AgCl pH 7) to reduce the complexes 1 and 2 to U IV complexes at pH 8.5, we re-examined the previously reported [10] interpretation of the cyclic voltammogram of 2 measured in water solution.…”

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

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

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“…Recently, we reported the synthesis and the structure of the uranyl(V) complex [K(2.2.2.cryptand)][UO 2 (dpaea)], 2 (dpaea 2− (bis(pyridyl‐6‐methyl‐2‐carboxylate)‐ethylamine), which was isolated from pyridine. Complex 2 disproportionates in acidic water conditions to yield the U VI [UO 2 (dpaea)], 1 and U IV [U(dpaea) 2 ] complexes, but it is stable in water at pH 7–11.…”

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confidence: 99%

“…We also investigated how the reduction of 1 is affected by pH. The reduction of [UO 2 (dpaea)] with Na 2 S 2 O 4 cannot be performed in acidic aqueous media (pH lower than 7) (Supporting Information, Figure S8) because the uranyl(V) [U V O 2 (dpaea)] − complex was found to disproportionate to [U VI O 2 (dpaea)] and [U IV (dpaea) 2 ] in these conditions . In contrast, no disproportionation is observed in water solutions of [NaUO 2 (dpaea)] at pH 8 to 11, but the reduction of U V to U IV is increasingly slower with increasing of pH.…”

Section: Methodsmentioning

confidence: 99%

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 UV and to UIV is important in uranium environmental migration and remediation processes. The anaerobic reduction of a uranyl UVI complex supported by a picolinate ligand in both organic and aqueous media is presented. The [UVIO2(dpaea)] complex is readily converted into the cis‐boroxide UIV species via diborane‐mediated reductive functionalization in organic media. Remarkably, in aqueous media the uranyl(VI) complex is rapidly converted, by Na2S2O4, a reductant relevant for chemical remediation processes, into the stable uranyl(V) analogue, which is then slowly reduced to yield a water‐insoluble trinuclear UIV oxo‐hydroxo cluster. This report provides the first example of direct conversion of a uranyl(VI) compound into a well‐defined molecular UIV species in aqueous conditions.

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Synthesis and Characterization of Water Stable Uranyl(V) Complexes

et al. 2021

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The importance of uranyl(V) (UO 2 +)s pecies associated with environmental and geologic applications is becoming increasingly evident, but the tendency of the uranyl-(V) cation to disproportionate in water has prevented the isolation of stable complexes.Here we demonstrate that in the presence of the tridentate complexing dipicolinate (dpa 2À), aligand highly abundant in soil, the uranyl(V) species can be stabilized and isolated in anoxic basic water.Stable uranyl(V) dipicolinate complexes are readily formed from the reduction of the uranyl(VI) analogue both in organic solution and in basic water,a nd their solution and solid-state structure were determined. Ab is-dpa U V O 2 + complex was obtained from water at pH 10, while at higher pH values,atrinuclear monodpa cation-cation complex was isolated. These results present the second ever isolated water stable uranyl(V) complex. Moreover,w ed emonstrate that dipicolinate complexes of U VI O 2 2+ ,U V O 2 + and U IV are strongly luminescent with asignature characteristic of each oxidation state.This provides unique examples of luminescent U V and U IV compounds.

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Synthesis and Characterization of a Water Stable Uranyl(V) Complex

Cited by 47 publications

References 62 publications

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

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

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

Synthesis and Characterization of Water Stable Uranyl(V) Complexes

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