Structural Characterization and Redox Activity of a Uranyl Dimer and Transition-Metal Complexes of a Tetradentate BIAN Ligand

Niklas, Julie E.; Farnum, Byron H.; Gorden, John D.; Gorden, Anne E. V.

doi:10.1021/acs.organomet.7b00454

Cited by 17 publications

(18 citation statements)

References 63 publications

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“…The cathodic peak potentials ( E pc ) are about ‐0.7 and ‐1.0 V. The differential pulse voltammograms of 1 ‐ 3 display two well‐resolved peaks at potentials around ‐0.65 and ‐0.88 V. The voltammograms of a representative complex is shown in Figure . Considering that the present complexes are diacetate bridged dinuclear species and complexes of trans ‐(UO 2 ) 2+ with Schiff bases are known to display U(VI) to U(V) reduction response at comparable potential range,‐,, the reductions observed for 1 ‐ 3 can be assigned as U(VI)‐U(VI) → U(V)‐U(VI) and U(V)‐U(VI) → U(V)‐U(V) processes. However, the free Schiff bases (HL n ) are also redox active and display a single reduction response having large peak‐to‐peak separation ( E pc and E pa values are around ‐1.02 and ‐0.04 V, respectively) and cathodic peak current ( i pc ) to anodic peak current ( i pa ) ratio.…”

Section: Resultsmentioning

confidence: 95%

Di‐μ‐acetato Diuranyl(VI) Complexes with N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene)hydrazines: Syntheses, Structures, Properties and Extraction Studies

et al. 2018

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Reactions of equimolar amounts of UO2(OAc)2⋅2H2O and N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene)hydrazines (HLn; n=1–3 for R = H, Me, and OMe, respectively) in methanol produced [(UO2)2(μ‐OAc)2(Ln)2] (1‐3 for n=1–3) in ∼70% yields. Elemental analysis, various spectroscopic, and electrochemical measurements were used to characterize 1‐3. X‐ray crystal structures revealed an 8‐membered U(OCO)2U ring with a chair conformation and pentagonal‐bipyramidal UN2O5 coordination spheres in each of 1‐3. The N,N,O‐donor (Ln)‐ and the two O‐atoms of the two bridging (OAc)‐ form the pentagonal plane around the U‐atom of trans‐(UO2)2+. Intermolecular H‐bonding assisted self‐assembly of the complexes lead to 1‐ and 2‐dimensional supramolecular structures. Infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectra of 1‐3 are consistent with their molecular structures. The electronic spectra showed four strong absorption bands in the range 466‐288 nm. The complexes undergo two irreversible reductions near ‐0.65 and ‐0.88 V (vs. Ag/AgCl). Time‐dependent density functional theory (TD‐DFT) calculations suggest that a ligand centered transition causes the highest energy absorption band, while, the remaining three are ligand‐to‐metal charge transfer (LMCT) bands and the two successive reductions are due to U(VI)‐U(VI) → U(V)‐U(VI) → U(V)‐U(V) processes. A maximum extraction of 98% of trans‐(UO2)2+ from the aqueous layer was observed in two‐phase extraction studies.

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Section: Resultsmentioning

confidence: 95%

Di‐μ‐acetato Diuranyl(VI) Complexes with N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene)hydrazines: Syntheses, Structures, Properties and Extraction Studies

et al. 2018

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“…The UO 2 + cation, and other actinyl(V) and actinyl(VI) cations, can coordinate other cations via their electron-donor O atoms, ,, a phenomenon commonly dubbed a cation–cation interaction (CCI). − In a CCI between two actinyl cations the interionic Coulomb repulsion is offset by attraction between a negatively charged oxygen atom of one actinyl and the positively charged actinide center of the other. Although a more elaborate and accurate description of this type of interaction might be as an “extreme dipole interaction between cationic molecules”, we retain the convenient conventional terminology of “CCI”, where the quotation marks, as employed by Guillaume et al, emphasize that the attractive interaction is an actinide–oxygen dipole interaction, not an interaction between bare atomic cations.…”

Section: Introductionmentioning

confidence: 99%

Destruction of the Uranyl Moiety in a U(V) “Cation–Cation” Interaction

Jian

et al. 2019

Inorg. Chem.

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A gas-phase uranyl peroxide dimer supported by three 12-Crown-4 ether (12C4) ligands, [(UO2)2(O2)(12C4)3)] 2+ (A), was prepared by electrospray ionization. Density functional theory (DFT) indicates a structure with two terminal 12C4 and the third 12C4 bridging the uranium centers. Collision induced dissociation (CID) of A resulted in elimination of the bridging 12C4 to yield a uranyl peroxide dimer with two terminal donor ligands, [(12C4)(UO2)(O2)(UO2)(12C4)] 2+ (B). Remarkably, CID of B resulted in elimination of the bridging peroxide concomitant with reduction of U(VI) to U(V) in C, [(12C4)(UO2)(UO2)(12C4)] 2+. DFT indicates that in C there is direct interaction between the two UO2 + , which can thus be considered as a so-called cation-cation interaction (CCI). This formal CCI, induced by tetradentate 12C4 ligands, corresponds to destruction of the linear uranyl moieties and creation of bridging U-O-U oxo-bonds. Based on the structural rearrangement to achieve the structurally extreme CCI interaction, it is predicted to also be accessible for PaO2 + , but is less feasible for transuranic actinyls.

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“…However, the use of redox-active ligands to promote electron transfer in f element compounds and in uranium chemistry ,, in particular remains significantly rarer than in d block chemistry. − …”

Section: Introductionmentioning

confidence: 99%

Carbon Dioxide Reduction by Multimetallic Uranium(IV) Complexes Supported by Redox-Active Schiff Base Ligands

et al. 2020

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The synthesis, structure, and reactivity with CO 2 and CS 2 of new U(IV) complexes with a redox-active Schiff base are reported. The reaction of UI 3 with the heptadentate Schiff base ligand 2,2′,2″-tris(salicylideneimino)triethylamine (trensal) did not lead to the formation of a U(III) complex but to the reductive coupling and C−C bond formation between two imino groups of the Schiff base, yielding the U(IV) complex [U 2 (bis-trensal)], 1. Further reduction of 1 led to the dinuclear macrocyclic complex [{K(THF) 3 } 2 U 2 (cyclotrensal)], 3-THF, through a second C−C bond formation reaction between two additional imino groups. Complexes 1 and 3 are oxidized by AgOTf resulting in the cleavage of the C−C bonds and leading to the formation of the U(IV) complex [U(trensal)]OTf, 2. Complex 1 does not reduce CO 2 or CS 2 but undergoes insertion of CO 2 into one of the U−N bonds. In contrast, the reaction of 3 with 2 equiv of CO 2 leads to the reductive disproportionation of CO 2 to afford carbonate in 80% yield. In the presence of a large excess of CO 2 multiple reactions take place, as supported by the isolation of the crystals of [{K(THF) 3 }U 2 (μ-O)(CO 2 −CO-cyclo-trensal)(U(trensal))], 4. The higher reductive activity toward CO 2 of complex 3 compared to previously reported U(IV) complexes of reduced Schiff bases is interpreted in terms of its redox properties.

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Structural Characterization and Redox Activity of a Uranyl Dimer and Transition-Metal Complexes of a Tetradentate BIAN Ligand

Cited by 17 publications

References 63 publications

Di‐μ‐acetato Diuranyl(VI) Complexes with N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene)hydrazines: Syntheses, Structures, Properties and Extraction Studies

Di‐μ‐acetato Diuranyl(VI) Complexes with N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene)hydrazines: Syntheses, Structures, Properties and Extraction Studies

Destruction of the Uranyl Moiety in a U(V) “Cation–Cation” Interaction

Carbon Dioxide Reduction by Multimetallic Uranium(IV) Complexes Supported by Redox-Active Schiff Base Ligands

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