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 redcolored 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) & ANGS;, 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) & ANGS; 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.

Keywords

Mixed-valence thallium(III)-thallium(I) complex; Red-colored complex; Dimethylsulfoxide; N; N'N'-tetramethyl urea; Structure; Decomposition rate

Published in

Journal of Molecular Liquids
2023, Volume: 385, article number: 122233
Publisher: ELSEVIER

SLU Authors

• Bajnóczi, Eva

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    
  • Hungarian Wigner Research Centre for Physics

• Persson, Ingmar

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Atom and Molecular Physics and Optics
Physical Chemistry


Publication identifier

DOI: https://doi.org/10.1016/j.molliq.2023.122233

Permanent link to this page (URI)

https://res.slu.se/id/publ/122997