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Title: Infrared Spectroscopy of Dioxouranium (V) Complexes with Solvent Molecules: Effect of Reduction

Abstract

UO2+-solvent complexes having the general formula [UO₂ (ROH)]+ (R = H, CH₃, C₂H₅, and n-C₃H₇) were formed using electrospray ionization and stored in a Fourier transform ion cyclotron resonance mass spectrometer, where they were isolated by mass-to-charge ratio, and then photofragmented using a free electron laser scanning through the 10 μm region of the infrared spectrum. Antisymmetric O=U=O stretching frequencies (ν3) were measured for all four complexes, which ranged from ~ 953 cm¯¹ for H₂O to ~ 944 cm¯¹ for n- PrOH, with the value for the EtOH-containing complex intermediate, systematically decreasing with increasing nucleophilicity of the solvent. The value for the MeOH-containing did not follow the trend, and had a measured ν3 value equal to that of the n-PrOH-containing complex. The ν3 frequency values for these U(V) complexes are comparable to those for the anionic [UO₂ (NO₃)₃]- complex, and lower than previously reported values for ligated uranyl (VI) dication complexes by 40 – 70 cm¯¹, and cationic uranyl (VI) ion-pair complexes by 10 – 40 cm¯¹. The lower frequency is attributed to weakening of the O=U=O bonds by repulsion related to reduction of the U metal center, which increases electron density in the antibonding π* orbitals of the uranylmore » moiety. Computational modelling of the ν3 frequencies of these species using PBE, B3LYP and LDA functionals showed good agreement with the IRMPD measurements. In general, expected trend in ν3 frequencies expected for the H₂O – MeOH – EtOH – n-PrOH series was produced by all three computational methods, however the three alcohols produced very similar values. The inverted order of MeOH and EtOH was not directly accounted for by the models, but is probably the result of overlapping C-H wagging modes that shift the apparent maxima of the O=U=O ν3 absorptions in the MeOH and EtOH complexes.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
937025
Report Number(s):
PNNL-SA-58694
Journal ID: ISSN 1439-4235; CPCHFT; 9598; KC0302030; TRN: US0806043
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Chemphyschem, 9(9):1278-1285
Additional Journal Information:
Journal Volume: 9; Journal Issue: 9; Journal ID: ISSN 1439-4235
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; URANYL COMPLEXES; INFRARED SPECTRA; SOLVENTS; ELECTRONIC STRUCTURE; FREQUENCY DEPENDENCE; MOLECULAR MODELS; Environmental Molecular Sciences Laboratory

Citation Formats

Groenewold, G S, Van Stipdonk, Michael J, De Jong, Wibe A, Oomens, Jos, Gresham, Garold L, McIIwain, Michael E, Gao, Da, Siboulet, Bertrand, Visscher, Lucas, Kullman, Michael, and Polfer, Nick. Infrared Spectroscopy of Dioxouranium (V) Complexes with Solvent Molecules: Effect of Reduction. United States: N. p., 2008. Web. doi:10.1002/cphc.200800034.
Groenewold, G S, Van Stipdonk, Michael J, De Jong, Wibe A, Oomens, Jos, Gresham, Garold L, McIIwain, Michael E, Gao, Da, Siboulet, Bertrand, Visscher, Lucas, Kullman, Michael, & Polfer, Nick. Infrared Spectroscopy of Dioxouranium (V) Complexes with Solvent Molecules: Effect of Reduction. United States. https://doi.org/10.1002/cphc.200800034
Groenewold, G S, Van Stipdonk, Michael J, De Jong, Wibe A, Oomens, Jos, Gresham, Garold L, McIIwain, Michael E, Gao, Da, Siboulet, Bertrand, Visscher, Lucas, Kullman, Michael, and Polfer, Nick. Tue . "Infrared Spectroscopy of Dioxouranium (V) Complexes with Solvent Molecules: Effect of Reduction". United States. https://doi.org/10.1002/cphc.200800034.
@article{osti_937025,
title = {Infrared Spectroscopy of Dioxouranium (V) Complexes with Solvent Molecules: Effect of Reduction},
author = {Groenewold, G S and Van Stipdonk, Michael J and De Jong, Wibe A and Oomens, Jos and Gresham, Garold L and McIIwain, Michael E and Gao, Da and Siboulet, Bertrand and Visscher, Lucas and Kullman, Michael and Polfer, Nick},
abstractNote = {UO2+-solvent complexes having the general formula [UO₂ (ROH)]+ (R = H, CH₃, C₂H₅, and n-C₃H₇) were formed using electrospray ionization and stored in a Fourier transform ion cyclotron resonance mass spectrometer, where they were isolated by mass-to-charge ratio, and then photofragmented using a free electron laser scanning through the 10 μm region of the infrared spectrum. Antisymmetric O=U=O stretching frequencies (ν3) were measured for all four complexes, which ranged from ~ 953 cm¯¹ for H₂O to ~ 944 cm¯¹ for n- PrOH, with the value for the EtOH-containing complex intermediate, systematically decreasing with increasing nucleophilicity of the solvent. The value for the MeOH-containing did not follow the trend, and had a measured ν3 value equal to that of the n-PrOH-containing complex. The ν3 frequency values for these U(V) complexes are comparable to those for the anionic [UO₂ (NO₃)₃]- complex, and lower than previously reported values for ligated uranyl (VI) dication complexes by 40 – 70 cm¯¹, and cationic uranyl (VI) ion-pair complexes by 10 – 40 cm¯¹. The lower frequency is attributed to weakening of the O=U=O bonds by repulsion related to reduction of the U metal center, which increases electron density in the antibonding π* orbitals of the uranyl moiety. Computational modelling of the ν3 frequencies of these species using PBE, B3LYP and LDA functionals showed good agreement with the IRMPD measurements. In general, expected trend in ν3 frequencies expected for the H₂O – MeOH – EtOH – n-PrOH series was produced by all three computational methods, however the three alcohols produced very similar values. The inverted order of MeOH and EtOH was not directly accounted for by the models, but is probably the result of overlapping C-H wagging modes that shift the apparent maxima of the O=U=O ν3 absorptions in the MeOH and EtOH complexes.},
doi = {10.1002/cphc.200800034},
url = {https://www.osti.gov/biblio/937025}, journal = {Chemphyschem, 9(9):1278-1285},
issn = {1439-4235},
number = 9,
volume = 9,
place = {United States},
year = {2008},
month = {5}
}