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Striking stability of a mixed-valence thallium(III)-thallium(I) complex in some solvents

Łyczko, Krzysztof ; Więckowska, Agnieszka ; Bajnoczi, Éva G. ; Csupász, Tibor ; Purgel, Mihály ; Sigfridsson Clauss, Kajsa G.V. LU ; Tóth, Imre and Persson, Ingmar (2023) In Journal of Molecular Liquids 385.
Abstract

At the dissolution of solid anhydrous thallium(III) trifluoromethanesulfonate, Tl(CF3SO3)3, or thallium(III) trifluoroacetate, Tl(CF3COO)3, in dimethylsulfoxide (dmso) or N,N,N’,N’-tetramethylurea (tmu), intensely red-colored complexes are formed. This red thallium complex is stable for years in dmso, while it is reduced fairly rapidly to thallium(I) in tmu with a half-life time of an hour. At the dissolution of Tl(CF3SO3)3 in N,N-dimethylpropyleneurea (dmpu) an immediate reduction to thallium(I) takes place. A stable colorless aqueous thallium(III) solution is obtained at the dissolution in acidic water. Stable dmso solutions and solid dmso solvates... (More)

At the dissolution of solid anhydrous thallium(III) trifluoromethanesulfonate, Tl(CF3SO3)3, or thallium(III) trifluoroacetate, Tl(CF3COO)3, in dimethylsulfoxide (dmso) or N,N,N’,N’-tetramethylurea (tmu), intensely red-colored complexes are formed. This red thallium complex is stable for years in dmso, while it is reduced fairly rapidly to thallium(I) in tmu with a half-life time of an hour. At the dissolution of Tl(CF3SO3)3 in N,N-dimethylpropyleneurea (dmpu) an immediate reduction to thallium(I) takes place. A stable colorless aqueous thallium(III) solution is obtained at the dissolution in acidic water. Stable dmso solutions and solid dmso solvates of thallium(III) perchlorate, nitrate and trifluormethanesulfonate can be prepared by adding dmso to concentrated acidic aqueous thallium(III) solutions. These experimental observations conclude that the pure solids Tl(CF3SO3)3 and Tl(CF3COO)3 play an essential role in the formation of the red-colored thallium complexes. 205Tl NMR data show that the red thallium complex contains equal amounts of thallium(III) and thallium(I). The structure of the red thallium complex in dmso, as determined by EXAFS, has Tl–O bond distances of 2.216(3) and 2.80(2) Å, which are in very close agreement with the bond distances obtained in the pure dmso solvates of the thallium(III) and thallium(I) ions, respectively, and a Tl···Tl distance of 3.49(1) Å bridged by oxygen atoms. From the EXAFS data it is impossible to distinguish if dmso molecules and/or trifluoromethanesulfonate ions act as bridges. DFT calculations could eliminate some structures due to the irrelevant structural parameters or the energetics of the proposed reactions.

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Contribution to journal
publication status
published
subject
keywords
Decomposition rate, Dimethylsulfoxide, Mixed-valence thallium(III)-thallium(I) complex, N, N, N'N’-tetramethyl urea, Red-colored complex, Structure
in
Journal of Molecular Liquids
volume
385
article number
122233
publisher
Elsevier
external identifiers
  • scopus:85162926390
ISSN
0167-7322
DOI
10.1016/j.molliq.2023.122233
language
English
LU publication?
yes
id
7efb1306-381c-40a0-8a27-eea34ceba575
date added to LUP
2023-08-30 14:19:29
date last changed
2023-08-30 14:19:29
@article{7efb1306-381c-40a0-8a27-eea34ceba575,
  abstract     = {{<p>At the dissolution of solid anhydrous thallium(III) trifluoromethanesulfonate, Tl(CF<sub>3</sub>SO<sub>3</sub>)<sub>3</sub>, or thallium(III) trifluoroacetate, Tl(CF<sub>3</sub>COO)<sub>3</sub>, in dimethylsulfoxide (dmso) or N,N,N’,N’-tetramethylurea (tmu), intensely red-colored complexes are formed. This red thallium complex is stable for years in dmso, while it is reduced fairly rapidly to thallium(I) in tmu with a half-life time of an hour. At the dissolution of Tl(CF<sub>3</sub>SO<sub>3</sub>)<sub>3</sub> in N,N-dimethylpropyleneurea (dmpu) an immediate reduction to thallium(I) takes place. A stable colorless aqueous thallium(III) solution is obtained at the dissolution in acidic water. Stable dmso solutions and solid dmso solvates of thallium(III) perchlorate, nitrate and trifluormethanesulfonate can be prepared by adding dmso to concentrated acidic aqueous thallium(III) solutions. These experimental observations conclude that the pure solids Tl(CF<sub>3</sub>SO<sub>3</sub>)<sub>3</sub> and Tl(CF<sub>3</sub>COO)<sub>3</sub> play an essential role in the formation of the red-colored thallium complexes. <sup>205</sup>Tl NMR data show that the red thallium complex contains equal amounts of thallium(III) and thallium(I). The structure of the red thallium complex in dmso, as determined by EXAFS, has Tl–O bond distances of 2.216(3) and 2.80(2) Å, which are in very close agreement with the bond distances obtained in the pure dmso solvates of the thallium(III) and thallium(I) ions, respectively, and a Tl···Tl distance of 3.49(1) Å bridged by oxygen atoms. From the EXAFS data it is impossible to distinguish if dmso molecules and/or trifluoromethanesulfonate ions act as bridges. DFT calculations could eliminate some structures due to the irrelevant structural parameters or the energetics of the proposed reactions.</p>}},
  author       = {{Łyczko, Krzysztof and Więckowska, Agnieszka and Bajnoczi, Éva G. and Csupász, Tibor and Purgel, Mihály and Sigfridsson Clauss, Kajsa G.V. and Tóth, Imre and Persson, Ingmar}},
  issn         = {{0167-7322}},
  keywords     = {{Decomposition rate; Dimethylsulfoxide; Mixed-valence thallium(III)-thallium(I) complex; N, N, N'N’-tetramethyl urea; Red-colored complex; Structure}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Molecular Liquids}},
  title        = {{Striking stability of a mixed-valence thallium(III)-thallium(I) complex in some solvents}},
  url          = {{http://dx.doi.org/10.1016/j.molliq.2023.122233}},
  doi          = {{10.1016/j.molliq.2023.122233}},
  volume       = {{385}},
  year         = {{2023}},
}