Two-Electron Three-Centered Bond in Side-On (η<sup>2</sup>) Uranyl(V) Superoxo Complexes

Bryantsev, Vyacheslav S.; Jong, Wibe A. de; Cossel, Kevin C.; Diallo, Mamadou S.; Goddard, William A.; Groenewold, Gary S.; Chien, Winnie; Stipdonk, Michael J. Van

doi:10.1021/jp804202q

Cited by 45 publications

(73 citation statements)

References 31 publications

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“…here to slightly underestimate bond strengths and corresponding stretching frequencies [69][70][71]86] ) and similar to those at 895-907 cm À1 for [{(thf)UO 2 ···MA C H T U N G T R E N N U N G (thf)}(L)] (M = Mn, Fe and Co), [25] 830 and 933 cm À1 for [UO 2 …”

Section: ···Ma C H T U N G T R E N N U N G (Thf)}(l)] (M = Mn and Co)supporting

confidence: 62%

Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

Pan

Shamov

Schreckenbach

2010

Chemistry A European J

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On the basis of uranyl complexes reacting with a polypyrrolic ligand (H(4)L), we explored structures and reaction energies of a series of new binuclear uranium(VI) complexes using relativistic density functional theory. Full geometry optimizations on [(UO(2))(2)(L)], in which two uranyl groups were initially placed into the pacman ligand cavity, led to two minimum-energy structures. These complexes with cation-cation interactions (CCI) exhibit unusual coordination modes of uranyls: one is a T-shaped (T) skeleton formed by two linear uranyls {O(exo)=U(2)=O(endo)-->U(1)(=O(exo))(2)}, and another is a butterfly-like (B) unit with one linear uranyl coordinating side-by-side to a second cis-uranyl. The CCI in T was confirmed by the calculated longest distance and lowest stretching vibrational frequency of U(2)=O(endo) among the four U=O bonds. Isomer B is more stable than T, for which experimental tetrameric analogues are known. The formation of B and T complexes from the mononuclear [(UO(2))(H(2)L)(thf)] (M) was found to be endothermic. The further protonation and dehydration of B and T are thermodynamically favorable. As a possible product, we have found a trianglelike binuclear uranium(VI) complex having a O=U=O=U=O unit.

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Section: ···Ma C H T U N G T R E N N U N G (Thf)}(l)] (M = Mn and Co)supporting

confidence: 62%

Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

Pan

Shamov

Schreckenbach

2010

Chemistry A European J

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“…In the positive‐going cycles, there were small irreversible waves with anodic peak currents in the range −0.66 to −0.62 V ( E pa ), which were correlated with the E pc value, and a small, quasi‐reversible couple with a half‐wave potential ( E 1/2 ) of −0.14 to −0.12 V near the high‐limit switching potential. This quasireversible process was attributed to the oxidation of the innermost peroxo ligands; the removal of electrons from the peroxo‐based HOMOs would lead to the formation of a superoxo complex that would be prone to disproportionation were it not stabilized by uranyl(V), as in calculations reported previously 14. In so far as the difference between the applied electrode potentials for the first reduction ( E pc =−0.99 V) and the first oxidation (−0.14≤ E 1/2 ≤−0.12 V) provided an electrochemical measure of the HOMO–LUMO gap,15 the experimental value of 0.9 V compares favorably with the calculated values (Table 2).…”

Section: Resultsmentioning

confidence: 63%

A Journey inside the U₂₈ Nanocapsule

Gil

Karhánek

Miró

et al. 2012

Chemistry A European J

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Anionic uranyl-peroxide U(28) nanocapsules trap cations and other anions inside, whose structures cannot be resolved by X-ray diffraction, owing to crystallographic disorder. DFT calculations enabled the complete characterization of the geometry of these complex systems and also explained the origin of the disorder. The stability of the capsules was strongly influenced by the entrapped cations. Excellent agreement between experiment and theory was also obtained for the electronic character and redox properties.

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“…A more reasonable explanation is that the O 2 moiety is a side-on bound superoxide ligand, analogous to those identified as products of reduced uranyl ([U(V)O 2 ] + ) and dioxygen. 103,104 The second lowest energy structure contained two oxo ligands, and a superoxide bound in a more conventional end-on arrangement. Three other structural alternatives were significantly higher in energy.…”

Section: Resultsmentioning

confidence: 99%

Cerium Oxyhydroxide Clusters: Formation, Structure, and Reactivity

Aubriet¹,

Gaumet²,

Jong

et al. 2009

J. Phys. Chem. A

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Cerium oxyhydroxide cluster anions were produced by irradiating ceric oxide particles by using 355 nm laser pulses that were synchronized with pulses of nitrogen gas admitted to the irradiation chamber. The gas pulse stabilized the nascent clusters that are largely anhydrous [Ce(x)O(y)] ions and neutrals. These initially formed species react with water, principally forming oxohydroxy species that are described by the general formula [Ce(x)O(y)(OH)(z)](-) for which all the Ce atoms are in the IV oxidation state. In general, the extent of hydroxylation varies from a value of three OH per Ce atom when x = 1 to a value slightly greater than 1 for x >or= 8. The Ce(3) and Ce(6) species deviate significantly from this trend: the x = 3 cluster accommodates more hydroxyl moieties compared to neighboring congeners at x = 2 and 4. Conversely, the x = 6 cluster is significantly less hydroxylated than its x = 5 and 7 neighbors. Density functional theory (DFT) modeling of the cluster structures shows that the hydrated clusters are hydrolyzed, and contain one-to-multiple hydroxide moieties, but not datively bound water. DFT also predicts an energetic preference for formation of highly symmetric structures as the size of the clusters increases. The calculated structures indicate that the ability of the Ce(3) oxyhydroxide to accommodate more extensive hydroxylation is due to a more open, hexagonal structure in which the Ce atoms can participate in multiple hydrolysis reactions. Conversely the Ce(6) oxyhydroxide has an octahedral structure that is not conducive to hydrolysis. In addition to the fully oxidized (Ce(IV)) oxyhydroxides, reduced oxyhydroxides (containing a Ce(III) center) are also formed. These become more prominent as the size of the clusters increases, suggesting that the larger ceria clusters have an increased ability to accommodate a reduced Ce(III) moiety. In addition, the spectra offer evidence for the formation of superoxide derivatives that may arise from reaction of the reduced oxyhydroxides with dioxygen. The overall intensity of the clusters tends to monotonically decrease as the cluster size increases; however, this trend is interrupted at Ce(13), which is significantly more stable compared to neighboring congeners, suggesting formation of a dehydrated Keggin-type structure.

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Two-Electron Three-Centered Bond in Side-On (η²) Uranyl(V) Superoxo Complexes

Cited by 45 publications

References 31 publications

Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

A Journey inside the U₂₈ Nanocapsule

Cerium Oxyhydroxide Clusters: Formation, Structure, and Reactivity

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Two-Electron Three-Centered Bond in Side-On (η2) Uranyl(V) Superoxo Complexes

Cited by 45 publications

References 31 publications

Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

Binuclear Uranium(VI) Complexes with a “Pacman” Expanded Porphyrin: Computational Evidence for Highly Unusual Bis‐Actinyl Structures

A Journey inside the U28 Nanocapsule

Cerium Oxyhydroxide Clusters: Formation, Structure, and Reactivity

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Product

Resources

About

Two-Electron Three-Centered Bond in Side-On (η²) Uranyl(V) Superoxo Complexes

A Journey inside the U₂₈ Nanocapsule