Halide Abstraction from Halogenated Acetate Ligands by Actinyls: A Competition between Bond Breaking and Bond Making

Dau, Phuong Diem; Gibson, John K.

doi:10.1021/acs.jpca.5b00952

Cited by 10 publications

(7 citation statements)

References 58 publications

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“…For all three An species, F atom transfer was also prevalent, producing [(F)AnO 2 (O 2 C–C 6 F 5 ) 2 ] − and [(F)(C 6 F 5 )AnO 2 (O 2 C–C 6 F 5 )] − . Similar halogen atom transfer was recently reported for actinyls coordinated by halogenated acetates …”

Section: Resultssupporting

confidence: 88%

Synthesis and Hydrolysis of Uranyl, Neptunyl, and Plutonyl Gas-Phase Complexes Exhibiting Discrete Actinide–Carbon Bonds

et al. 2016

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Gas-phase organoactinyl complexes possessing discrete An−C bonds (An = U, Np, Pu) were synthesized in a quadrupole ion trap by endothermic decarboxylation of [AnO 2 (O 2 C−R) 3 ]− anion complexes in which a formally AnO 2 2+ actinyl core is coordinated by three carboxylate ligands, with R = CH 3 (methyl), CH 3 CC (1-propynyl), C 6 H 5 (phenyl), C 6 F 5 (pentafluorophenyl). Decarboxylation and competing ligand loss were studied computationally by density functional theory complementing experiment. Although decarboxylation was computed to be the energetically most favorable process in all cases, reduction from An(VI) to An(V) via neutral ligand loss was often prevalent, particularly for An = Np, Pu, presumably resulting from barriers associated with decarboxylation. Comparative hydrolysis rates of the An−C bonds were experimentally determined, and the chemical properties of these bonds were analyzed by the quantum theory of atoms in molecules. The measured hydrolysis rates differed by up to 3 orders of magnitude: the fastest was for [(CH 3 CC)UO 2 (O 2 C− CCCH 3 ) 2 ]− and the slowest for [(C 6 F 5 )PuO 2 (O 2 C−C 6 F 5 ) 2 ]− . There is a general correlation between hydrolysis exothermicity and hydrolysis rate. Prototypical hydrolysis reaction pathways computed for R = CH 3 (An = U, Np) reveal a mechanism in which an outer-sphere water becomes inner-sphere concomitant with transfer of an H atom to yield an OH ligand and CH 4 , with a net energy release of 170 kJ mol −1 and a transition state barrier of 45 kJ mol −1 for An = U. Infrared multiphoton dissociation spectra of selected complexes were acquired to confirm the predicted structures by agreement between the computed and observed vibrational frequencies. The experiment and theory results provide an evaluation of the comparative propensities for formation of the organoactinyls as a function of actinide and carboxylate and an assessment of the nature and stability toward hydrolysis of the primarily ionic An−C bonds.

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Section: Resultssupporting

confidence: 88%

Synthesis and Hydrolysis of Uranyl, Neptunyl, and Plutonyl Gas-Phase Complexes Exhibiting Discrete Actinide–Carbon Bonds

et al. 2016

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“…Retention of the U(VI) oxidation state is achieved by abstraction of a fluoride anion from the ligand, a phenomenon that has been previously observed and reflects the high affinity of uranium for fluorine. 53 In contrast (Fig. 3b) is water-addition to yield [(UO 2 ) 2 (OH) 2 (L) 2 ] 2+ , the structure of which was computed to be a bridging bis-hydroxide.…”

Section: Synthesis and Reactivity Of Gas-phase Uranyl Dimer Cation Comentioning

confidence: 99%

A Uranyl Peroxide Dimer in the Gas Phase

Dau

Rao

et al. 2017

Inorg. Chem.

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The gas-phase uranyl peroxide dimer, [(UO)(O)(L)] where L = 2,2'-trifluoroethylazanediyl)bis(N,N'-dimethylacetamide), was synthesized by electrospray ionization of a solution of UO and L. Collision-induced dissociation of this dimer resulted in endothermic O atom elimination to give [(UO)(O)(L)], which was found to spontaneously react with water via exothermic hydrolytic chemisorption to yield [(UO)(OH)(L)]. Density functional theory computations of the energies for the gas-phase reactions are in accord with observations. The structures of the observed uranyl dimer were computed, with that of the peroxide of particular interest, as a basis to evaluate the formation of condensed phase uranyl peroxides with bent structures. The computed dihedral angle in [(UO)(O)(L)] is 145°, indicating a substantial deviation from the planar structure with a dihedral angle of 180°. Energies needed to induce bending in the most elementary gas-phase uranyl peroxide complex, [(UO)(O)], were computed. It was found that bending from the lowest-energy planar structure to dihedral angles up to 140° required energies of <10 kJ/mol. The gas-phase results demonstrate the inherent stability of the uranyl peroxide moiety and support the notion that the uranyl-peroxide-uranyl structural unit is intrinsically planar, with only minor energy perturbations needed to form the bent structures found in studtite and uranyl peroxide nanostructures.

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“…The utility of ESI-MS and CID for assessing structures and bonding of halide complexes has been described. [47][48] For Xa= Cl and Xb = Br (Figure 1a), the dominant observed gas-phase complexes from ESI were…”

Section: Esi Mass Spectrometrymentioning

confidence: 99%

Halide anion discrimination by a tripodal hydroxylamine ligand in gas and condensed phases

Cheisson

Jian

et al. 2019

Phys. Chem. Chem. Phys.

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Halide Abstraction from Halogenated Acetate Ligands by Actinyls: A Competition between Bond Breaking and Bond Making

Cited by 10 publications

References 58 publications

Synthesis and Hydrolysis of Uranyl, Neptunyl, and Plutonyl Gas-Phase Complexes Exhibiting Discrete Actinide–Carbon Bonds

Synthesis and Hydrolysis of Uranyl, Neptunyl, and Plutonyl Gas-Phase Complexes Exhibiting Discrete Actinide–Carbon Bonds

A Uranyl Peroxide Dimer in the Gas Phase

Halide anion discrimination by a tripodal hydroxylamine ligand in gas and condensed phases

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