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Title: Infrared Spectroscopy of Discrete Uranyl Anion Complexes

Abstract

The Free-Electron Laser for Infrared Experiments, FELIX, was used to study the wavelength-resolved multiphoton dissociation of discrete, gas phase uranyl (UO22+) complexes containing a single anionic ligand (A), with or without ligated solvent molecules (S). The apparent 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 = 0-2. 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 using B3LYP predicted values that were 30 – 40 cm-1 higher, consistent with intuition but not with the data. Modification of the basis set 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 resulted only very modest changes to the uranyl frequency, and did not universally shiftmore » values lower. 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:
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Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - SC
OSTI Identifier:
923516
Report Number(s):
INL/JOU-07-12193
TRN: US200804%%1210
DOE Contract Number:  
DE-AC07-99ID-13727
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A
Additional Journal Information:
Journal Volume: 112; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACCURACY; ACETATES; ACETONE; ACETONITRILE; AMMONIA; ANIONS; DISSOCIATION; FREE ELECTRON LASERS; FUNCTIONALS; HYDROXIDES; MODIFICATIONS; SOLVENTS; SPECTROSCOPY; WATER; Free-Electron Laser for Infrared Experiments; gas phase uranyl (UO22+) complexes; neutral nucleophilicity

Citation Formats

Groenewold, Gary S, Gianotto, Anita K, McIlwain, Michael E, Van Stipdonk, Michael J, Kullman, Michael, Cooper, Travis J, Moore, David T, Polfer, Nick, Oomens, Jos, Infante, Ivan, Visscher, Lucas, Siboulet, Bertrand, and de Jong, Wibe A. Infrared Spectroscopy of Discrete Uranyl Anion Complexes. United States: N. p., 2007. Web.
Groenewold, Gary S, Gianotto, Anita K, McIlwain, Michael E, Van Stipdonk, Michael J, Kullman, Michael, Cooper, Travis J, Moore, David T, Polfer, Nick, Oomens, Jos, Infante, Ivan, Visscher, Lucas, Siboulet, Bertrand, & de Jong, Wibe A. Infrared Spectroscopy of Discrete Uranyl Anion Complexes. United States.
Groenewold, Gary S, Gianotto, Anita K, McIlwain, Michael E, Van Stipdonk, Michael J, Kullman, Michael, Cooper, Travis J, Moore, David T, Polfer, Nick, Oomens, Jos, Infante, Ivan, Visscher, Lucas, Siboulet, Bertrand, and de Jong, Wibe A. Sat . "Infrared Spectroscopy of Discrete Uranyl Anion Complexes". United States.
@article{osti_923516,
title = {Infrared Spectroscopy of Discrete Uranyl Anion Complexes},
author = {Groenewold, Gary S and Gianotto, Anita K and McIlwain, Michael E and Van Stipdonk, Michael J and Kullman, Michael and Cooper, Travis J and Moore, David T and Polfer, Nick and Oomens, Jos and Infante, Ivan and Visscher, Lucas and Siboulet, Bertrand and de Jong, Wibe A},
abstractNote = {The Free-Electron Laser for Infrared Experiments, FELIX, was used to study the wavelength-resolved multiphoton dissociation of discrete, gas phase uranyl (UO22+) complexes containing a single anionic ligand (A), with or without ligated solvent molecules (S). The apparent 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 = 0-2. 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 using B3LYP predicted values that were 30 – 40 cm-1 higher, consistent with intuition but not with the data. Modification of the basis set 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 resulted only very modest changes to the uranyl frequency, and did not universally shift values lower. 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 = {},
journal = {Journal of Physical Chemistry A},
number = 3,
volume = 112,
place = {United States},
year = {2007},
month = {12}
}