Mixed-Ligand Uranyl(V) β-Diketiminate/β-Diketonate Complexes: Synthesis and Characterization

Hayton, Trevor W.; Wu, Guang

doi:10.1021/ic800778j

Cited by 60 publications

(61 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[27,29] To prevent the formation of polynuclear intermediates leading to disproportionation ours and other groups have designed bulky polydentate ligands or macrocyclic ligands that have resulted in the preparation of stable complexes of pentavalent uranyl. [21,[31][32][33][34] These initial results seemed to validate the general assumption that the formation of cation-cation complexes would inevitably result in the disproportionation of the pentavalent uranyl species.…”

Section: Introductionmentioning

confidence: 53%

Cation–Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

Mougel¹,

Horeglad²,

Nocton³

et al. 2010

Chemistry A European J

View full text Add to dashboard Cite

Three new cation-cation complexes of pentavalent uranyl, stable with respect to the disproportionation reaction, have been prepared from the reaction of the precursor [(UO(2)py(5))(KI(2)py(2))](n) (1) with the Schiff base ligands salen(2-), acacen(2-), and salophen(2-) (H(2)salen = N,N'-ethylene-bis(salicylideneimine), H(2)acacen = N,N'-ethylenebis(acetylacetoneimine), H(2)salophen = N,N'-phenylene-bis(salicylideneimine)). The preparation of stable complexes requires a careful choice of counter ions and reaction conditions. Notably the reaction of 1 with salophen(2-) in pyridine leads to immediate disproportionation, but in the presence of [18]crown-6 ([18]C-6) a stable complex forms. The solid-state structure of the four tetranuclear complexes, {[UO(2)(acacen)](4)[μ(8)-](2)[K([18]C-6)(py)](2)} (3) and {[UO(2)(acacen)](4)[μ(8)-]}⋅2 [K([222])(py)] (4), {[UO(2)(salophen)](4)[μ(8)-K](2)[μ(5)-KI](2)[(K([18]C-6)]}⋅2 [K([18]C-6)(thf)(2)]⋅2 I (5), and {[UO(2)(salen)(4)][μ(8)-Rb](2)[Rb([18]C-6)](2)} (9) ([222] = [222]cryptand, py = pyridine), presenting a T-shaped cation-cation interaction has been determined by X-ray crystallographic studies. NMR spectroscopic and UV/Vis studies show that the tetranuclear structure is maintained in pyridine solution for the salen and acacen complexes. Stable mononuclear complexes of pentavalent uranyl are also obtained by reduction of the hexavalent uranyl Schiff base complexes with cobaltocene in pyridine in the absence of coordinating cations. The reactivity of the complex [U(V)O(2)(salen)(py)][Cp*(2)Co] with different alkali ions demonstrates the crucial effect of coordinating cations on the stability of cation-cation complexes. The nature of the cation plays a key role in the preparation of stable cation-cation complexes. Stable tetranuclear complexes form in the presence of K(+) and Rb(+), whereas Li(+) leads to disproportionation. A new uranyl-oxo cluster was isolated from this reaction. The reaction of [U(V)O(2)(salen)(py)][Cp*(2)Co] (Cp* = pentamethylcyclopentadienyl) with its U(VI) analogue yields the oxo-functionalized dimer [UO(2)(salen)(py)](2)[Cp*(2)Co] (8). The reaction of the {[UO(2)(salen)(4)][μ(8)-K](2)[K([18]C-6)](2)} tetramer with protons leads to disproportionation to U(IV) and U(VI) species and H(2)O confirming the crucial role of the proton in the U(V) disproportionation.

show abstract

Section: Introductionmentioning

confidence: 53%

Cation–Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

Mougel¹,

Horeglad²,

Nocton³

et al. 2010

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…However, two structures with (V) and (VI) oxidation states of uranyl species are reported by Berthet et al, [55] and Hayton and Gu. [56] In Berthet et al structure, triphenyl phosphine oxide ligand coordinated to uranyl in both oxidation states. We have calculated the structures and detachment energies for this complex.…”

Section: Redox Properties Of Crystallographically Known U(v) Complexmentioning

confidence: 99%

Predicting the redox properties of uranyl complexes using electronic structure calculations

Khungar

Roy

Kumar

et al. 2017

Int J of Quantum Chemistry

View full text Add to dashboard Cite

A plethora of chemical reactions is redox driven processes. The conversion of toxic and highly soluble U(VI) complexes to nontoxic and insoluble U(IV) form are carried out through proton coupled electron transfer by iron containing cytochromes and mineral surfaces such as machinawite. This redox process takes place through the formation of U(V) species which is unstable and immediately undergo the disproportionation reaction. Thus, theoretical methods are extremely useful to understand the reduction process of U(VI) to U(V) species. We here have carried out the structures and reduction properties of several U(VI) to U(V) complexes using a variety of electronic structure methods. Due to the lack of experimental ionization energies for uranyl (UO2(V)‐UO2(VI)) couple, we have benchmarked the current and popularly used density functionals and cost effective ab initio methods against the experimental electron detachment energies of [UO2F4]1‐/2‐ and [UO2Cl4]1‐/2‐. We find that electron detachment energy of U(VI) predicted by RI‐MP2 level on the BP86 geometries correlate nicely with the experimental and CCSD(T) data. Based on our benchmark studies, we have predicted the structures and electron detachment energies of U(V) to U(VI) species for a series of uranium complexes at the RI‐MP2//BP86 level which are experimentally inaccessible till date. We find that the redox active molecular orbital is ligand centered for the oxidation of U(VI) species, where it is metal centered (primarily f‐orbital) for the oxidation of U(V) species. Finally, we have also calculated the detachment energies of a known uranyl [UO2]1+ complex whose X‐ray crystal structures of both oxidation states are available. The large bulky nature of the ligand stabilizing the uncommon U(V) species which cannot be routinely studied by present day CCSD(T) methods as the system size are more than 20–30 atoms. The success of our efficient computational strategy can be experimentally verified in the near future for the complex as the structures are stable in gas phase which can undergo oxidation.

show abstract

“…Hayton and co-workers have also examined the chemi stry of ~-diketiminate/~-diketonate uranyl complexes of the type U02(Ar2nacnac)(RC(O)CHC(O)R) (Ar2nacnac bis(2,6 diisopropylphenyl)pentane-2,4-di-iminato; R = Me, Ph, U VI CF 3 ) 38 Electrochemical analysis of the complexes 40 showed that there was a systematic decrease in the UV1/U V reduction potentials with variation of the R group in the ~ diketonate ligand (R = Me (22), UV1/ U V = -1.82 V; R = Ph (23), UV1/ U V = -1.59 V; R = CF 3 (24), UV1/ U V = -\. 39 The resultant reduction products were discrete cation/anion pairs:…”

Section: Synthesis and Characterization Of Vot Complexes In Solutionmentioning

confidence: 99%

Pentavalent uranium chemistry—synthetic pursuit of a rare oxidation state

2009

View full text Add to dashboard Cite

Mixed-Ligand Uranyl(V) β-Diketiminate/β-Diketonate Complexes: Synthesis and Characterization

Cited by 60 publications

References 64 publications

Cation–Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

Cation–Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

Predicting the redox properties of uranyl complexes using electronic structure calculations

Pentavalent uranium chemistry—synthetic pursuit of a rare oxidation state

Contact Info

Product

Resources

About