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Variable Denticity in Carboxylate Binding to the Uranyl Coordination Complexes
Tris-carboxylate complexes of uranyl [UO 2] 2+ with acetate and benzoate were generated using electrospray ionization mass spectrometry, and then isolated in a Fourier transform ion cyclotron resonance mass spectrometer. Wavelength-selective infrared multiple photon dissociation (IRMPD) of the tris-...
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Published in: | Journal of the American Society for Mass Spectrometry 2010-05, Vol.21 (5), p.719-727 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Tris-carboxylate complexes of uranyl [UO
2]
2+ with acetate and benzoate were generated using electrospray ionization mass spectrometry, and then isolated in a Fourier transform ion cyclotron resonance mass spectrometer. Wavelength-selective infrared multiple photon dissociation (IRMPD) of the
tris-acetato uranyl anion resulted in a redox elimination of an acetate radical, which was used to generate an IR spectrum that consisted of six prominent absorption bands. These were interpreted with the aid of density functional theory calculations in terms of symmetric and antisymmetric −CO
2 stretches of the monodentate and bidentate acetate, CH
3 bending and umbrella vibrations, and a uranyl O–U–O asymmetric stretch. The comparison of the calculated and measured IR spectra indicated that the predominant conformer of the
tris-acetate complex contained two acetate ligands bound in a bidentate fashion, while the third acetate was monodentate. In similar fashion, the
tris-benzoate uranyl anion was formed and photodissociated by loss of a benzoate radical, enabling measurement of the infrared spectrum that was in close agreement with that calculated for a structure containing one monodentate and two bidentate benzoate ligands.
Infrared multiple photon dissociation spectroscopy shows that uranyl
tris-carboxylate complexes have ligands coordinated in both bidentate and monodentate modes. |
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ISSN: | 1044-0305 1879-1123 |
DOI: | 10.1016/j.jasms.2010.01.021 |