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Structure and water exchange of the hydrated thiosulfate ion in aqueous solution using QMCF MD simulation and large angle X-ray scattering

Eklund, Lars and Hofer, Thomas S. and Weiss, Alexander and Tirler, Andreas and Persson, Ingmar (2014). Structure and water exchange of the hydrated thiosulfate ion in aqueous solution using QMCF MD simulation and large angle X-ray scattering. Dalton Transactions: an international journal of inorganic chemistry [incorporating Acta Chemica Scandinavica]. 43:33, 12711-12720
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Official URL: http://www.dx.doi.org/10.1039/c4dt01010h

Abstract

Theoretical ab initio quantum mechanical charge field molecular dynamics (QMCF MD) has been applied in conjunction with experimental large angle X-ray scattering (LAXS) to study the structure and dynamics of the hydrated thiosulfate ion, S2O32-, in aqueous solution. The S-O and S-C-S-T bond distances have been determined to be 1.479(5) and 2.020(6) angstrom by LAXS and to be 1.478 and 2.017 angstrom by QMCF MD simulations, which are slightly longer than the mean values found in the solid state, 1.467 and 2.002 angstrom, respectively. This is due to the hydrogen bonds formed at hydration. The water dynamics show that water molecules are exchanged at the hydrated oxygen and sulfur atoms, and that the water exchange is ca. 50% faster at the sulfur atom than at the oxygen atoms with mean residence times, tau(0.5), of 2.4 and 3.6 ps, respectively. From this point of view the water exchange dynamics mechanism resembles the sulfate ion, while it is significantly different from the sulfite ion. This shows that the lone electron-pair in the sulfite ion has a much larger impact on the water exchange dynamics than a substitution of an oxygen atom for a sulfur one. The LAXS data did give mean S-C...O-aq1 and S-C...O-aq2 distances of 3.66(2) and 4.36(10) angstrom, respectively, and S-C-O-thio and O-thio...O-aq1, S-C-S-T and S-T...O-aq2 distances of 1.479(5), 2.845(10), 2.020(6) and 3.24(5) angstrom, respectively, giving S-C-O-thio...O-aq1 and S-C-S-T...O-aq2 angles close to 110 degrees, strongly indicating a tetrahedral geometry around the terminal thiosulfate sulfur and the oxygens, and thereby, three water molecules are hydrogen bound to each of them. The hydrogen bonds between thiosulfate oxygens and the hydrating water molecules are stronger and with longer mean residence times than those between water molecules in the aqueous bulk, while the opposite is true for the hydrogen bonds between the terminal thiosulfate sulfur and the hydrating water molecules. The hydration of all oxo sulfur ions is discussed using the detailed observations for the sulfate, thiosulfate and sulfite ions, and the structure of the hydrated peroxodisulfate ion, S2O82-, in aqueous solution has been determined by means of LAXS to support the general observations. The mean S-O bond distances are 1.448(2) and 1.675(5) angstrom to the oxo and peroxo oxygens, respectively.

Authors/Creators:Eklund, Lars and Hofer, Thomas S. and Weiss, Alexander and Tirler, Andreas and Persson, Ingmar
Title:Structure and water exchange of the hydrated thiosulfate ion in aqueous solution using QMCF MD simulation and large angle X-ray scattering
Series/Journal:Dalton Transactions: an international journal of inorganic chemistry [incorporating Acta Chemica Scandinavica] (1477-9226)
Year of publishing :2014
Volume:43
Number:33
Page range:12711-12720
Number of Pages:10
Publisher:Royal Society of Chemistry
ISSN:1477-9226
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Accepted version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Inorganic Chemistry
Keywords:thiosulfate ion, aqueous solution, water exchange dynamics, QMCF MD simulation, large angle X-ray scattering
URN:NBN:urn:nbn:se:slu:epsilon-e-2273
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-2273
Additional ID:
Type of IDID
Web of Science (WoS)000340353100026
DOI10.1039/c4dt01010h
ID Code:11557
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Chemistry and Biotechnology (140101-161231)
External funders:Swedish Research Council
Deposited By: SLUpub Connector
Deposited On:18 Dec 2014 12:59
Metadata Last Modified:26 Jul 2015 23:15

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