Oxygen Exchange in Uranyl Hydroxide via Two “Nonclassical” Ions

Strongly coupled binuclear uranium–oxo complexes from uranyl oxo rearrangement and reductive silylation

“…The 1 H nuclear magnetic resonance (NMR) spectrum of 2a is consistent with its high symmetry and paramagnetism, displaying eight resonances between +14.8 and -11 ppm. Furthermore, a resonance at 160 ppm in the 29 Si NMR spectrum can be tentatively assigned to the SiMe 3 group of the newlysilylated oxo group. The FTIR spectrum of 2a contains bands at 862 and 802 cm -1 assigned to U-O stretches that are weakened and desymmetrised with respect to 1 (ν U=O 908 cm -1 ), and a Si-O stretch at 1100 cm -1 ; these data support the assignment of the pentavalent oxidation state.…”

“…The cisisomer appears to play a particularly important role in ligand exchange processes between uranium centres in uranyl hydroxides and aquo complexes [21][22][23][24][25] , species that are prevalent in high pH nuclear wastes [26][27][28] . In acid solutions, both T-shaped tris(oxo) and cis-uranyl geometries have been invoked as intermediates in proton transfer reactions that lead to uranyl oxo-group exchange, a process which remains poorly-understood [29][30][31][32] . Also, uranium lies directly below the Group 6 transition metals whose dioxo complexes are widespread in both enzymatic and industrial oxidation catalysis 33 and can adopt either the cisor trans-dioxo geometry, depending on d-electron configuration.…”

Double uranium oxo cations derived from uranyl by borane or silane reduction

“…This makes reduced uranium oxo compounds better models for the heavier, highly radioactive transuranic metal actinyl cations [AnO 2 ] n + (An = Np, Pu; n = 1, 2) for which clustering behaviour is problematic in PUREX separation processes for civil nuclear waste treatment. 3 – 6 Actinide oxo-bridges also facilitate electron-transfer reactions in environmental waste remediation, 7 – 9 enrich the coordination chemistry of actinides in minerals, 10 and can generate interesting electronic and magnetic structures. 11 – 13 …”

Aqueous solutions: state of the art in ab initio molecular dynamics

“…In particular, these studies include a large variety of metallic oxides and complexes where the properties of the system strongly depend on both the pH and the concentration of the metallic species [154][155][156][157][158][159][160][161][162][163][164][165][166]. For example, in the case of molybdenum, these studies have unravelled the influence of pH on species such as MoO 2 (OH) 2 [161].…”

“…Owing to the increase in computational power, the development of highly scalable algorithms and the improvement of theoretical approaches over the last 20 years, the AIMD methodology has further been applied to more chemically complex ions and inorganic species in water. In particular, these studies include a large variety of metallic oxides and complexes where the properties of the system strongly depend on both the pH and the concentration of the metallic species [154][155][156][157][158][159][160][161][162][163][164][165][166]. For example, in the case of molybdenum, these studies have unravelled the influence of pH on species such as MoO 2 (OH) 2 [161].…”