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Journal Articles Journal of Physical Chemistry A Year : 2007

Hydration of Hg2+ in Aqueous Solution Studied by Neutron Diffraction with Isotopic Substitution

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Abstract

The structural parameters of Hg2+ hydration were studied in 0.225 mol/L solutions of Hg2+ in DNO3/D2O by means of neutron diffraction with isotopic substitution of 199Hg for natHg. It was found that Hg2+ is hydrated by a first solvation shell of six water molecules. The observed Hg−O and Hg−H distances are equal to 2.48 ± 0.05 and 3.08 ± 0.05 Å, respectively. The angle phi between the plane of the water molecule and the cation−water oxygen axis is 35°. The solvation of Hg2+ therefore mimics very closely that of Ca2+ (the Ca−O and Ca−H distances are 2.40 and 3.03 Å, respectively) and helps to account for the extreme toxicity of mercury(II). We note also that the Hg−O distance obtained in the neutron diffraction experiment is larger by 0.1 Å than that obtained by X-ray diffraction. This difference is consistent with a shift of the oxygen electron density toward the mercury cation due to the covalency of the Hg−O interaction.

Dates and versions

insu-00347890 , version 1 (17-12-2008)

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Cite

O. Sobolev, G. J. Cuello, G. Roman Ross, N. T. Skipper, L. Charlet. Hydration of Hg2+ in Aqueous Solution Studied by Neutron Diffraction with Isotopic Substitution. Journal of Physical Chemistry A, 2007, 111 (24), pp.5123 à 5125. ⟨10.1021/jp072650w⟩. ⟨insu-00347890⟩
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