Perrhenate Complexation by Uranyl in Traditional Solvents and in Ionic Liquids: A Joint Molecular Dynamics/Spectroscopic Study - IN2P3 - Institut national de physique nucléaire et de physique des particules Access content directly
Journal Articles Journal of Physical Chemistry B Year : 2012

Perrhenate Complexation by Uranyl in Traditional Solvents and in Ionic Liquids: A Joint Molecular Dynamics/Spectroscopic Study

O. Klimchuk
  • Function : Author
C. Gaillard
C. Hennig
  • Function : Author
G. Wipff
  • Function : Author

Abstract

The complexation of perrhenate (ReO4-) anions by the uranyl (UO22+) cation has been investigated by joint molecular dynamics simulations and spectroscopic (UV-vis, TRLFS, and EXAFS) studies in aqueous solution, acetonitrile, and three ionic liquids (ILs), namely, [Bmi][Tf2N], [Me3BuN][Tf2N], and [Bu3MeN][Tf2N] that are based on the same Tf2N- anion (bis(trifluoromethylsulfonyl)imide) and either Bmi+ (1-butyl,3-methylimidazolium), Me3BuN+, or Bu3MeN+ cations. They show that ReO4- behaves as a weak ligand in aqueous solution and as a strong ligand in acetonitrile and in the ILs. According to MD simulations in aqueous solution, the UO2(ReO4)2 complex quickly dissociates to form UO2(H2O)52+, while in acetonitrile, a stable UO2(ReO4)53- species forms from dissociated ions. In the ILs, the UO2(ReO4)n2-n complexes (n = 1 to 5) remained stable along the dynamics, and to assess their relative stabilities, we computed the free energy profiles for stepwise ReO4- complexation to uranyl. In the two studied ILs, complexation is favored, leading to the UO2(ReO4)53- species in [Bmi][Tf2N] and to UO2(ReO4)42- in [Bu3MeN][Tf2N]. Furthermore, in both acetonitrile and [Bmi][Tf2N] solutions, MD and PMF simulations support the formation of dimeric uranyl complexes [UO2(ReO4)4]24- with two bridging ReO4- ligands. The simulation results are qualitatively consistent with spectroscopic observations in the different solvents, without firmly concluding, however, on the precise composition and structure of the complexes in the solutions.
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Dates and versions

in2p3-00690834 , version 1 (24-04-2012)

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A. Chaumont, O. Klimchuk, C. Gaillard, I. Billard, A. Ouadi, et al.. Perrhenate Complexation by Uranyl in Traditional Solvents and in Ionic Liquids: A Joint Molecular Dynamics/Spectroscopic Study. Journal of Physical Chemistry B, 2012, 116, pp.3205-3219. ⟨10.1021/jp209476h⟩. ⟨in2p3-00690834⟩
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