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Title: Vibrational Spectroscopy of Mass Selected [UO2(ligand)n]2+ Complexes in the Gas Phase

Abstract

The gas-phase infrared spectra of discrete uranyl ([UO2]2+) complexes ligated with acetone and/or acetonitrile were used to evaluate systematic trends of ligation on the position of the O=U=O stretch, and to enable rigorous comparison with the results of computational studies. Ionic uranyl complexes isolated in a Fourier transform ion cyclotron resonance mass spectrometer were fragmented via infrared multiphoton dissociation using a free electron laser scanned over the mid-IR wavelengths. The asymmetric O=U=O stretching frequency was measured at 1017 cm-1 for [UO2(CH3COCH3)2]2+, and was systematically red shifted to 1000 and 988 cm-1 by the addition of a third and fourth acetone ligands, respectively, which was consistent with more donation of electron density to the uranium center in complexes with higher coordination number. The experimental measurements were in good agreement with values generated computationally using LDA, B3LYP, and ZORA-PW91 approaches. In contrast to the uranyl frequency shifts, the carbonyl frequencies of the acetone ligands were progressively blue shifted as the number of ligands increased from 2 to 4, and approached that of free acetone. This observation was consistent with the formation of weaker noncovalent bonds between uranium and the carbonyl oxygen as the extent of ligation increases. Similar trends were observed formore » [UO2(CH3CN)n]2+ complexes although the magnitude of the red shift in the uranyl frequency upon addition more acetonitrile ligands was smaller than for acetone, consistent with the more modest nucleophilic nature of acetonitrile. This conclusion was amplified by the uranyl stretching frequencies measured for mixed acetone/acetonitrile complexes, which showed that substitution of one acetone for one acetonitrile produced a modest red shift of 3 to 6 cm-1.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - EM
OSTI Identifier:
912416
Report Number(s):
INL/JOU-05-00908
Journal ID: ISSN 0002-7863; JACSAT; TRN: US200801%%847
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal Am. Chem. Soc.; Journal Volume: 128; Journal Issue: 14
Country of Publication:
United States
Language:
English
Subject:
37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACETONE; ACETONITRILE; CARBONYLS; COORDINATION NUMBER; DISSOCIATION; ELECTRON DENSITY; FREE ELECTRON LASERS; INFRARED SPECTRA; ION CYCLOTRON-RESONANCE; MASS SPECTROMETERS; OXYGEN; RED SHIFT; SPECTROSCOPY; URANIUM; URANYL COMPLEXES; WAVELENGTHS; gas-phase; UO2 ligands; vibrational spectroscopy

Citation Formats

Gary S. Groenewold, Anita Gianotto, Michael Vanstipdonk, Kevin C. Cossel, David T. Moore,, Nick Polfer, and Jos Oomens. Vibrational Spectroscopy of Mass Selected [UO2(ligand)n]2+ Complexes in the Gas Phase. United States: N. p., 2006. Web. doi:10.1021/ja058106n.
Gary S. Groenewold, Anita Gianotto, Michael Vanstipdonk, Kevin C. Cossel, David T. Moore,, Nick Polfer, & Jos Oomens. Vibrational Spectroscopy of Mass Selected [UO2(ligand)n]2+ Complexes in the Gas Phase. United States. doi:10.1021/ja058106n.
Gary S. Groenewold, Anita Gianotto, Michael Vanstipdonk, Kevin C. Cossel, David T. Moore,, Nick Polfer, and Jos Oomens. 2006. "Vibrational Spectroscopy of Mass Selected [UO2(ligand)n]2+ Complexes in the Gas Phase". United States. doi:10.1021/ja058106n.
@article{osti_912416,
title = {Vibrational Spectroscopy of Mass Selected [UO2(ligand)n]2+ Complexes in the Gas Phase},
author = {Gary S. Groenewold and Anita Gianotto and Michael Vanstipdonk and Kevin C. Cossel and David T. Moore, and Nick Polfer and Jos Oomens},
abstractNote = {The gas-phase infrared spectra of discrete uranyl ([UO2]2+) complexes ligated with acetone and/or acetonitrile were used to evaluate systematic trends of ligation on the position of the O=U=O stretch, and to enable rigorous comparison with the results of computational studies. Ionic uranyl complexes isolated in a Fourier transform ion cyclotron resonance mass spectrometer were fragmented via infrared multiphoton dissociation using a free electron laser scanned over the mid-IR wavelengths. The asymmetric O=U=O stretching frequency was measured at 1017 cm-1 for [UO2(CH3COCH3)2]2+, and was systematically red shifted to 1000 and 988 cm-1 by the addition of a third and fourth acetone ligands, respectively, which was consistent with more donation of electron density to the uranium center in complexes with higher coordination number. The experimental measurements were in good agreement with values generated computationally using LDA, B3LYP, and ZORA-PW91 approaches. In contrast to the uranyl frequency shifts, the carbonyl frequencies of the acetone ligands were progressively blue shifted as the number of ligands increased from 2 to 4, and approached that of free acetone. This observation was consistent with the formation of weaker noncovalent bonds between uranium and the carbonyl oxygen as the extent of ligation increases. Similar trends were observed for [UO2(CH3CN)n]2+ complexes although the magnitude of the red shift in the uranyl frequency upon addition more acetonitrile ligands was smaller than for acetone, consistent with the more modest nucleophilic nature of acetonitrile. This conclusion was amplified by the uranyl stretching frequencies measured for mixed acetone/acetonitrile complexes, which showed that substitution of one acetone for one acetonitrile produced a modest red shift of 3 to 6 cm-1.},
doi = {10.1021/ja058106n},
journal = {Journal Am. Chem. Soc.},
number = 14,
volume = 128,
place = {United States},
year = 2006,
month = 3
}
  • The gas-phase infrared spectra of discrete uranyl ([UO₂]²⁺) complexes ligated with acetone and/or acetonitrile were used to evaluate systematic trends of ligation on the position of the O=U=O stretch, and to enable rigorous comparison with the results of computational studies. Ionic uranyl complexes isolated in a Fourier transform ion cyclotron resonance mass spectrometer were fragmented via infrared multiphoton dissociation using a free electron laser scanned over the mid-IR wavelengths. The asymmetric O=U=O stretching frequency was measured at 1017 cm⁻¹ for [UO₂(CH₃COCH₃)₂]²⁺ and was systematically red shifted to 1000 and 988 cm⁻¹ by the addition of a third and fourth acetonemore » ligand, respectively, which was consistent with increased donation of electron density to the uranium center in complexes with higher coordination number. The values generated computationally using LDA, B3LYP, and ZORA-PW91 were in good agreement with experimental measurements. In contrast to the uranyl frequency shifts, the carbonyl frequencies of the acetone ligands were progressively blue shifted as the number of ligands increased from 2 to 4, and approached that of free acetone. This observation was consistent with the formation of weaker noncovalent bonds between uranium and the carbonyl oxygen as the extent of ligation increases. Similar trends were observed for [UO₂(CH₃CN)n]²⁺ complexes, although the magnitude of the red shift in the uranyl frequency upon addition of more acetonitrile ligands was smaller than for acetone, consistent with the more modest nucleophilic nature of acetonitrile. This conclusion was confirmed by the uranyl stretching frequencies measured for mixed acetone/acetonitrile complexes, which showed that substitution of one acetone for one acetonitrile produced a modest red shift of 3 to 6 cm⁻¹.« less
  • The gas-phase infrared spectra of discrete uranyl ([UO2]2+) complexes ligated with acetone and/or acetonitrile were used to evaluate systematic trends of ligation on the position of the OdUdO stretch and to enable rigorous comparison with the results of computational studies. Ionic uranyl complexes isolated in a Fourier transform ion cyclotron resonance mass spectrometer were fragmented via infrared multiphoton dissociation using a free electron laser scanned over the mid-IR wavelengths. The asymmetric OdUdO stretching frequency was measured at 1017 cm-1 for [UO2(CH3COCH3)2]2+ and was systematically red shifted to 1000 and 988 cm-1 by the addition of a third and fourth acetonemore » ligand, respectively, which was consistent with increased donation of electron density to the uranium center in complexes with higher coordination number. The values generated computationally using LDA, B3LYP, and ZORA-PW91 were in good agreement with experimental measurements. In contrast to the uranyl frequency shifts, the carbonyl frequencies of the acetone ligands were progressively blue shifted as the number of ligands increased from two to four and approached that of free acetone. This observation was consistent with the formation of weaker noncovalent bonds between uranium and the carbonyl oxygen as the extent of ligation increases. Similar trends were observed for [UO2(CH3CN)n]2+ complexes, although the uranyl asymmetric stretching frequencies were greater than those measured for acetone complexes having equivalent coordination, which is consistent with the fact that acetonitrile is a weaker nucleophile than is acetone. This conclusion was confirmed by the uranyl stretching frequencies measured for mixed acetone/acetonitrile complexes, which showed that substitution of one acetone for one acetonitrile produced a modest red shift of 3-6 cm-1.« less
  • Organometallic complexes immobilized on surfaces combine the high selectivity of homogeneous catalysts with the ease of separation of catalyst from products of heterogeneous materials. Here we report a novel approach for the highly controlled preparation of surface organometallic catalysts by gas-phase ligand stripping combined with reactive landing of mass-selected ions onto self assembled monolayer surfaces. Collision induced dissociation is used to generate highly reactive undercoordinated metal complexes in the gas-phase for subsequent surface immobilization. Complexes with an open coordination shell around the metal center are demonstrated to show enhanced activity towards reactive landing in comparison to fully ligated species. Inmore » situ TOF-SIMS analysis indicates that the immobilized complexes exhibit behaviour consistent with catalytic activity when exposed to gaseous reagents.« less
  • Infrared spectra of the mass-selected clusters H{sub 3}O{sup +}{sm bullet}(H{sub 2}O){sub n}{sm bullet}(H{sub 2}) and H{sub 3}O{sup +}{sm bullet}(H{sub 2}){sub n} (n = 1,2, and 3) were observed by vibrational predissociation spectroscopy. The clusters were mass-selected and then trapped in a radio frequency ion trap. Cluster dissociation by loss of H{sub 2} followed excitation of OH or H{sub 2} stretches. Spectra were recorded by detecting fragment ions as a function of laser frequency. From spectra of H{sub 3}O{sup +}{sm bullet}(H{sub 2}O){sub n}{sm bullet}(H{sub 2}), the authors were able to determine the spectrum of the hydrated hydronium ion H{sub 3}O{sup +}{smmore » bullet}(H{sub 2}O){sub n}, because the H{sub 2} formed weak complexes with the hydrates. Spectra in the OH stretching region (3,000-4,000 cm{sup {minus}1}) were observed at a resolution of 1.3 cm{sup {minus}1} for clusters n = 1,2, and 3. The structure of the clusters and the perturbing effect of the H{sub 2} were inferred from a comparison with recent unpublished ab initio vibrational frequencies calculated by Remington and Schaefer.« less
  • Experiments have been undertaken to record photofragmentation spectra from a series of [Ag(L){sub N}]{sup 2+} complexes in the gas phase. Spectra have been obtained for silver(II) complexed with the ligands (L): acetone, 2-pentanone, methyl-vinyl ketone, pyridine, and 4-methyl pyridine (4-picoline) with N in the range of 4-7. A second series of experiments using 1,1,1,3-fluoroacetone, acetonitrile, and CO{sub 2} as ligands failed to show any evidence of photofragmentation. Interpretation of the experimental data has come from time-dependent density functional theory (TDDFT), which very successfully accounts for trends in the spectra in terms of subtle differences in the properties of the ligands.more » Taking a sample of three ligands, acetone, pyridine, and acetonitrile, the calculations show all the spectral transitions to involve ligand-to-metal charge transfer, and that wavelength differences (or lack of spectra) arise from small changes in the energies of the molecular orbitals concerned. The calculations account for an absence in the spectra of any effects due to Jahn-Teller distortion, and they also reveal structural differences between complexes where the coordinating atom is either oxygen or nitrogen that have implications for the stability of silver(II) compounds. Where possible, comparisons have also been made with the physical properties of condensed phase silver(II) complexes.« less