Speciation and Coordination Chemistry of Uranyl(VI)-Citrate Complexes in Aqueous Solution

Sofie P. Pasilis; Jeanne E. Pemberton

doi:10.1021/ic0341800

Speciation and Coordination Chemistry of Uranyl(VI)-Citrate Complexes in Aqueous Solution

Sofie P. Pasilis, Jeanne E. Pemberton

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Abstract

The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the ν_s(UO₂) envelope indicate that three major UO ₂²⁺-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO₂²⁺ groups in spectroscopically equivalent coordination environments and corresponds to the [(UO₂)₂Cit ₂]^2- complex known to exist in this pH range. At pH values >6.5, [(UO₂)₂Cit₂]^2- undergoes ah an interconversion to form [(UO₂)₃Cit ₃]^3- and (UO₂)₃Cit₂. ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.

Original language	English (US)
Pages (from-to)	6793-6800
Number of pages	8
Journal	Inorganic Chemistry
Volume	42
Issue number	21
DOIs	https://doi.org/10.1021/ic0341800
State	Published - Oct 20 2003

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

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@article{6bb748f573ec46acb74c7cedee763248,

title = "Speciation and Coordination Chemistry of Uranyl(VI)-Citrate Complexes in Aqueous Solution",

abstract = "The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the νs(UO2) envelope indicate that three major UO 22+-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO22+ groups in spectroscopically equivalent coordination environments and corresponds to the [(UO2)2Cit 2]2- complex known to exist in this pH range. At pH values >6.5, [(UO2)2Cit2]2- undergoes ah an interconversion to form [(UO2)3Cit 3]3- and (UO2)3Cit2. ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.",

author = "Pasilis, {Sofie P.} and Pemberton, {Jeanne E.}",

year = "2003",

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day = "20",

doi = "10.1021/ic0341800",

language = "English (US)",

volume = "42",

pages = "6793--6800",

journal = "Inorganic Chemistry",

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publisher = "American Chemical Society",

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T1 - Speciation and Coordination Chemistry of Uranyl(VI)-Citrate Complexes in Aqueous Solution

AU - Pasilis, Sofie P.

AU - Pemberton, Jeanne E.

PY - 2003/10/20

Y1 - 2003/10/20

N2 - The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the νs(UO2) envelope indicate that three major UO 22+-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO22+ groups in spectroscopically equivalent coordination environments and corresponds to the [(UO2)2Cit 2]2- complex known to exist in this pH range. At pH values >6.5, [(UO2)2Cit2]2- undergoes ah an interconversion to form [(UO2)3Cit 3]3- and (UO2)3Cit2. ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.

AB - The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the νs(UO2) envelope indicate that three major UO 22+-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO22+ groups in spectroscopically equivalent coordination environments and corresponds to the [(UO2)2Cit 2]2- complex known to exist in this pH range. At pH values >6.5, [(UO2)2Cit2]2- undergoes ah an interconversion to form [(UO2)3Cit 3]3- and (UO2)3Cit2. ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.

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JO - Inorganic Chemistry

JF - Inorganic Chemistry

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ER -

Speciation and Coordination Chemistry of Uranyl(VI)-Citrate Complexes in Aqueous Solution

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