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Title: Infared Spectroscopy of Discrete Uranyl Anion Complexes

Abstract

The Free-Electron Laser for Infrared Experiments (FELIX) w 1 as used to study the wavelength-resolved multiple photon photodissociation of discrete, gas phase uranyl (UO2 2 2+) complexes containing a single anionic ligand (A), with or without ligated solvent molecules (S). The uranyl antisymmetric and symmetric stretching frequencies were measured for complexes with general formula [UO2A(S)n]+, where A was either hydroxide, methoxide, or acetate; S was water, ammonia, acetone, or acetonitrile; and n = 0-3. The values for the antisymmetric stretching frequency for uranyl ligated with only an anion ([UO2A]+) were as low or lower than measurements for [UO2]2+ ligated with as many as five strong neutral donor ligands, and are comparable to solution phase values. This result was surprising because initial DFT calculations predicted values that were 30–40 cm-1 higher, consistent with intuition but not with the data. Modification of the basis sets and use of alternative functionals improved computational accuracy for the methoxide and acetate complexes, but calculated values for the hydroxide were greater than the measurement regardless of the computational method used. Attachment of a neutral donor ligand S to [UO2A]+ produced [UO2AS]+, which produced only very modest changes to the uranyl antisymmetric stretch frequency, and did notmore » universally shift the frequency to lower values. DFT calculations for [UO2AS]+ were in accord with trends in the data, and showed that attachment of the solvent was accommodated by weakening of the U-anion bond as well as the uranyl. When uranyl frequencies were compared for [UO2AS]+ species having different solvent neutrals, values decreased with increasing neutral nucleophilicity.« less

Authors:
; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
924047
Report Number(s):
PNNL-SA-57425
9598; TRN: US0802008
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A, 112(3):508-521
Additional Journal Information:
Journal Volume: 112; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; ACETATES; ACETONE; ACETONITRILE; AMMONIA; ANIONS; FREE ELECTRON LASERS; FUNCTIONALS; HYDROXIDES; MODIFICATIONS; PHOTONS; SOLVENTS; SPECTROSCOPY; WATER; Environmental Molecular Sciences Laboratory

Citation Formats

Groenewold, G S, Gianotto, Anita K, McIIwain, Michael E, Van Stipdonk, Michael J, Kullman, Michael, Moore, David T, Polfer, Nick, Oomens, Jos, Infante, Ivan A, Visscher, Lucas, Siboulet, Bertrand, and De Jong, Wibe A. Infared Spectroscopy of Discrete Uranyl Anion Complexes. United States: N. p., 2008. Web. doi:10.1021/jp077309q.
Groenewold, G S, Gianotto, Anita K, McIIwain, Michael E, Van Stipdonk, Michael J, Kullman, Michael, Moore, David T, Polfer, Nick, Oomens, Jos, Infante, Ivan A, Visscher, Lucas, Siboulet, Bertrand, & De Jong, Wibe A. Infared Spectroscopy of Discrete Uranyl Anion Complexes. United States. doi:10.1021/jp077309q.
Groenewold, G S, Gianotto, Anita K, McIIwain, Michael E, Van Stipdonk, Michael J, Kullman, Michael, Moore, David T, Polfer, Nick, Oomens, Jos, Infante, Ivan A, Visscher, Lucas, Siboulet, Bertrand, and De Jong, Wibe A. Thu . "Infared Spectroscopy of Discrete Uranyl Anion Complexes". United States. doi:10.1021/jp077309q.
@article{osti_924047,
title = {Infared Spectroscopy of Discrete Uranyl Anion Complexes},
author = {Groenewold, G S and Gianotto, Anita K and McIIwain, Michael E and Van Stipdonk, Michael J and Kullman, Michael and Moore, David T and Polfer, Nick and Oomens, Jos and Infante, Ivan A and Visscher, Lucas and Siboulet, Bertrand and De Jong, Wibe A},
abstractNote = {The Free-Electron Laser for Infrared Experiments (FELIX) w 1 as used to study the wavelength-resolved multiple photon photodissociation of discrete, gas phase uranyl (UO2 2 2+) complexes containing a single anionic ligand (A), with or without ligated solvent molecules (S). The uranyl antisymmetric and symmetric stretching frequencies were measured for complexes with general formula [UO2A(S)n]+, where A was either hydroxide, methoxide, or acetate; S was water, ammonia, acetone, or acetonitrile; and n = 0-3. The values for the antisymmetric stretching frequency for uranyl ligated with only an anion ([UO2A]+) were as low or lower than measurements for [UO2]2+ ligated with as many as five strong neutral donor ligands, and are comparable to solution phase values. This result was surprising because initial DFT calculations predicted values that were 30–40 cm-1 higher, consistent with intuition but not with the data. Modification of the basis sets and use of alternative functionals improved computational accuracy for the methoxide and acetate complexes, but calculated values for the hydroxide were greater than the measurement regardless of the computational method used. Attachment of a neutral donor ligand S to [UO2A]+ produced [UO2AS]+, which produced only very modest changes to the uranyl antisymmetric stretch frequency, and did not universally shift the frequency to lower values. DFT calculations for [UO2AS]+ were in accord with trends in the data, and showed that attachment of the solvent was accommodated by weakening of the U-anion bond as well as the uranyl. When uranyl frequencies were compared for [UO2AS]+ species having different solvent neutrals, values decreased with increasing neutral nucleophilicity.},
doi = {10.1021/jp077309q},
journal = {Journal of Physical Chemistry A, 112(3):508-521},
number = 3,
volume = 112,
place = {United States},
year = {2008},
month = {1}
}