Oxygen exchange in uranyl hydroxide via two "nonclassical" ions

Michael Buehl; Georg Schreckenbach

doi:10.1021/ic902508z

Oxygen exchange in uranyl hydroxide via two "nonclassical" ions

Michael Buehl, Georg Schreckenbach

Research output: Contribution to journal › Article › peer-review

Abstract

A recently proposed pathway for the scrambling of axial (uranyl) and equatorial 0 atoms in [UO₂(OH)₄]^2- (1) is refined using Car-Parrinello molecular dynamics (CPMD) simulations in an explicit solvent (water) and with model counterions (NH₄⁺). According to constrained CPMD/BLYP simulations and thermodynamic integration, 1 can be deprotonated to [UO₃(OH)₃]^3- with a T-shaped UO₃ group (Delta A = 7.1 kcal/mol), which in turn can undergo a solvent-assisted proton transfer via a cis-[UO₂(OH)₄]^2-center dot OH^- complex and a total overall barrier of Delta A(double dagger) = 12.5 kcal/mol. According to computed relative energies of trans- and cis-[UO₂(OH)₄]^2- in the gas phase and in a polarizable continuum, "pure" functionals such as BLYP underestimate this overall barrier somewhat, and estimates of Delta A(double dagger) approximate to 16 and 17 kcal/mol are obtained at the B3LYP and CCSD(T) levels, respectively, in excellent agreement with the experiment.

Original language	English
Pages (from-to)	3821-3827
Number of pages	7
Journal	Inorganic Chemistry
Volume	49
Issue number	8
Early online date	24 Mar 2010
DOIs	https://doi.org/10.1021/ic902508z
Publication status	Published - 19 Apr 2010

Keywords

Density-functional theory
1st-principles molecular-dynamics
Polarizable continuum model
Main-group thermochemistry
Aqueous-solution
Noncovalent interactions
Free-energy
Basis-sets
AB-initio
Complexes

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10.1021/ic902508z

yl-exchange in [UO2(OH)4]2-
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society, after peer review and technical editing by the publisher. To access the final edited and published work see DOI: 10.1021/ic902508z
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Cite this

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title = "Oxygen exchange in uranyl hydroxide via two {"}nonclassical{"} ions",

abstract = "A recently proposed pathway for the scrambling of axial (uranyl) and equatorial 0 atoms in [UO2(OH)4]2- (1) is refined using Car-Parrinello molecular dynamics (CPMD) simulations in an explicit solvent (water) and with model counterions (NH4+). According to constrained CPMD/BLYP simulations and thermodynamic integration, 1 can be deprotonated to [UO3(OH)3]3- with a T-shaped UO3 group (Delta A = 7.1 kcal/mol), which in turn can undergo a solvent-assisted proton transfer via a cis-[UO2(OH)4]2-center dot OH- complex and a total overall barrier of Delta A(double dagger) = 12.5 kcal/mol. According to computed relative energies of trans- and cis-[UO2(OH)4]2- in the gas phase and in a polarizable continuum, {"}pure{"} functionals such as BLYP underestimate this overall barrier somewhat, and estimates of Delta A(double dagger) approximate to 16 and 17 kcal/mol are obtained at the B3LYP and CCSD(T) levels, respectively, in excellent agreement with the experiment.",

keywords = "Density-functional theory, 1st-principles molecular-dynamics, Polarizable continuum model, Main-group thermochemistry, Aqueous-solution, Noncovalent interactions, Free-energy, Basis-sets, AB-initio, Complexes",

author = "Michael Buehl and Georg Schreckenbach",

year = "2010",

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doi = "10.1021/ic902508z",

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T1 - Oxygen exchange in uranyl hydroxide via two "nonclassical" ions

AU - Buehl, Michael

AU - Schreckenbach, Georg

PY - 2010/4/19

Y1 - 2010/4/19

N2 - A recently proposed pathway for the scrambling of axial (uranyl) and equatorial 0 atoms in [UO2(OH)4]2- (1) is refined using Car-Parrinello molecular dynamics (CPMD) simulations in an explicit solvent (water) and with model counterions (NH4+). According to constrained CPMD/BLYP simulations and thermodynamic integration, 1 can be deprotonated to [UO3(OH)3]3- with a T-shaped UO3 group (Delta A = 7.1 kcal/mol), which in turn can undergo a solvent-assisted proton transfer via a cis-[UO2(OH)4]2-center dot OH- complex and a total overall barrier of Delta A(double dagger) = 12.5 kcal/mol. According to computed relative energies of trans- and cis-[UO2(OH)4]2- in the gas phase and in a polarizable continuum, "pure" functionals such as BLYP underestimate this overall barrier somewhat, and estimates of Delta A(double dagger) approximate to 16 and 17 kcal/mol are obtained at the B3LYP and CCSD(T) levels, respectively, in excellent agreement with the experiment.

AB - A recently proposed pathway for the scrambling of axial (uranyl) and equatorial 0 atoms in [UO2(OH)4]2- (1) is refined using Car-Parrinello molecular dynamics (CPMD) simulations in an explicit solvent (water) and with model counterions (NH4+). According to constrained CPMD/BLYP simulations and thermodynamic integration, 1 can be deprotonated to [UO3(OH)3]3- with a T-shaped UO3 group (Delta A = 7.1 kcal/mol), which in turn can undergo a solvent-assisted proton transfer via a cis-[UO2(OH)4]2-center dot OH- complex and a total overall barrier of Delta A(double dagger) = 12.5 kcal/mol. According to computed relative energies of trans- and cis-[UO2(OH)4]2- in the gas phase and in a polarizable continuum, "pure" functionals such as BLYP underestimate this overall barrier somewhat, and estimates of Delta A(double dagger) approximate to 16 and 17 kcal/mol are obtained at the B3LYP and CCSD(T) levels, respectively, in excellent agreement with the experiment.

KW - Density-functional theory

KW - 1st-principles molecular-dynamics

KW - Polarizable continuum model

KW - Main-group thermochemistry

KW - Aqueous-solution

KW - Noncovalent interactions

KW - Free-energy

KW - Basis-sets

KW - AB-initio

KW - Complexes

U2 - 10.1021/ic902508z

DO - 10.1021/ic902508z

M3 - Article

SN - 0020-1669

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SP - 3821

EP - 3827

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 8

ER -

Oxygen exchange in uranyl hydroxide via two "nonclassical" ions

Abstract

Keywords

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