Thallium(I) chloride

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Thallium(I) chloride
CsCl polyhedra.png
Thallium(I) chloride.jpg
IUPAC names
Thallium monochloride
Thallium(I) chloride
Other names
Thallous chloride
3D model (JSmol)
ECHA InfoCard 100.029.311
Molar mass 239.836 g/mol[1]
Appearance white, odorless crystalline solid[1]
Density 7.0 g/cm3[1]
Melting point 431 °C (808 °F; 704 K)[1]
Boiling point 720 °C (1,328 °F; 993 K)[1]
3.3 g/L (25 °C)[1]
Solubility insoluble in alcohol[1]
−57.8·10−6 cm3/mol[2]
2.247 (0.59 µm)
2.198 (0.75 µm)
2.145 (1 µm)
1.891 (5 µm)
2.193 (20 µm)[3]
CsCl, cP2
Pm3m, No. 221[4]
a = 0.38416 nm
0.0567 nm3
Cubic (Tl+)
Cubic (Cl)
Safety data sheet
Very toxic (T+)
Dangerous for the environment (N)
R-phrases (outdated) R26/28, R33, R51/53
S-phrases (outdated) (S1/2), S13, S28, S45, S61
Lethal dose or concentration (LD, LC):
24 mg/kg, oral, mouse
Related compounds
Other anions
Thallium(I) fluoride
Thallium(I) bromide
Thallium(I) iodide
Other cations
Thallium(III) chloride
Silver(I) chloride
Lead(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Thallium(I) chloride, also known as thallous chloride, is a chemical compound with the formula TlCl. This colourless solid is an intermediate in the isolation of thallium from its ores. Typically, an acidic solution of thallium(I) sulfate is treated with hydrochloric acid to precipitate insoluble thallium(I) chloride. This solid crystallizes in the caesium chloride motif.[5]

The low solubility of TlCl is exploited in chemical synthesis: treatment of metal chloride complexes with TlPF6, gives the corresponding metal hexafluorophosphate derivative. The resulting TlCl precipitate is separated by filtration of the reaction mixture. The overall methodology is similar to the use of AgPF6, except that Tl+ is much less oxidizing.

The crystalline structure is of cubic caesium chloride type at room temperature, but it lowers to the orthorhombic thallium iodide type upon cooling, the transition temperature being likely affected by the impurities.[6] Nanometer-thin TlCl films grown on KBr substrates exhibit a rocksalt structure, while the films deposited on mica or NaCl are of the regular CsCl type.[7]

A very rare mineral lafossaite, Tl(Cl,Br), is a natural form of thallium(I) chloride.[8]

Thallium(I) chloride, like all thallium compounds, is highly toxic, although its low solubility limits its toxicity.[9]


  1. ^ a b c d e f g Haynes, p. 4.94
  2. ^ Haynes, p. 4.135
  3. ^ Haynes, p. 10.242
  4. ^ Müürsepp, T.; Haav, A. (1974). "X-ray diffraction study of the systems TlI-CsI, TlI-RbI, and TlI-Tl Cl". Physica Status Solidi (a). 21 (2): K81. doi:10.1002/pssa.2210210251. 
  5. ^ Holleman, A. F.; Wiberg, E. Inorganic Chemistry. Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  6. ^ Blackman, M; Khan, I H (1961). "The Polymorphism of Thallium and Other Halides at Low Temperatures". Proceedings of the Physical Society. 77 (2): 471. doi:10.1088/0370-1328/77/2/331. 
  7. ^ Schulz, L. G. (1951). "Polymorphism of cesium and thallium halides". Acta Crystallographica. 4 (6): 487. doi:10.1107/S0365110X51001641. 
  8. ^ Lafossaite.
  9. ^ Thallium Chloride Material Safety Data Sheet.

Cited sources[edit]