Liem-Nguyen, Van and Skyllberg, Ulf and Kwangho, Nam and Björn, Erik
(2017).
Thermodynamic stability of mercury(II) complexes formed with environmentally relevant low-molecular-mass thiols studied by competing ligand exchange and density functional theory.
Environmental Chemistry. 14
:4
, 243-253
[Journal article]
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- Accepted Version
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Official URL: http://dx.doi.org/10.1071/EN17062
Abstract
Inorganic divalent mercury (Hg-II) has a very high affinity for reduced sulfur functional groups. Reports from laboratory experiments suggest that Hg-II complexes with specific low-molecular-mass (LMM) thiol (RSH) ligands control rates of Hg-II transformation reactions. Because of methodological limitations for precise determination of the highly stable Hg-II complexes with LMM thiol ligands, constants reported in the literature remain inconsistent. This uncertainty impedes accurate modelling of the chemical speciation of Hg-II and the possibility to elucidate the role of Hg-II complexes with LMM thiols for Hg transformation reactions. Here, we report values of thermodynamic stability constants for 15 monodentate, two-coordinated Hg-II complexes, Hg(SR)(2), formed with biogeochemically relevant LMM thiol ligands. The constants were determined by a two-step ligand-exchange procedure where the specific Hg(SR)(2) complexes were quantified by liquid chromatography-inductively coupled plasma mass spectrometry. Thermodynamic stability constants (log (2)) determined for the Hg(SR)(2) complexes ranged from 34.6, N-cysteinylglycine, to 42.1, 3-mercaptopropionic acid, for the general reaction Hg2++2RS(-) Hg(SR)(2). Density functional theory (DFT) calculations showed that electron-donating carboxyl and carbonyl groups have a stabilising effect on the Hg-II-LMM thiol complexes, whereas electron-withdrawing protonated primary amino groups have a destabilising effect. Experimental results and DFT calculations demonstrated that the presence of such functional groups in the vicinity of the RSH group caused significant differences in the stability of Hg(SR)(2) complexes. These differences are expected to be important for the chemical speciation of Hg-II and its transformation reactions in environments where a multitude of LMM thiol compounds are present.
Authors/Creators: | Liem-Nguyen, Van and Skyllberg, Ulf and Kwangho, Nam and Björn, Erik | ||||
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Title: | Thermodynamic stability of mercury(II) complexes formed with environmentally relevant low-molecular-mass thiols studied by competing ligand exchange and density functional theory | ||||
Series/Journal: | Environmental Chemistry (1449-8979) | ||||
Year of publishing : | 2017 | ||||
Volume: | 14 | ||||
Number: | 4 | ||||
Page range: | 243-253 | ||||
Number of Pages: | 11 | ||||
Publisher: | CSIRO Publishing | ||||
ISSN: | 1449-8979 | ||||
Language: | English | ||||
Publication Type: | Journal article | ||||
Refereed: | Yes | ||||
Article category: | Scientific peer reviewed | ||||
Version: | Accepted version | ||||
Full Text Status: | Public | ||||
Agris subject categories.: | X Agricola extesions > X50 Chemistry | ||||
Subjects: | (A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Organic Chemistry | ||||
Keywords: | Alkaline Aqueous-Solution, Nuclear Magnetic-Resonance, Human-Erythrocytes, Amino-Acids, Methylation, Glutathione, Cysteine, Constants, Hg(Ii), Thermochemistry | ||||
URN:NBN: | urn:nbn:se:slu:epsilon-e-4795 | ||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4795 | ||||
Additional ID: |
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ID Code: | 14887 | ||||
Faculty: | S - Faculty of Forest Sciences | ||||
Department: | (S) > Dept. of Forest Ecology and Management | ||||
Deposited By: | SLUpub Connector | ||||
Deposited On: | 08 Mar 2018 08:43 | ||||
Metadata Last Modified: | 08 Mar 2018 08:43 |
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