Thallium(I) iodide

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Thallium(I) iodide
Thallium(I) iodide
Names
Other names
Thallium monoiodide
Thallous iodide
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.029.272 Edit this at Wikidata
EC Number
  • 232-199-7
UNII
  • InChI=1S/HI.Tl/h1H;/q;+1/p-1 checkY
    Key: CMJCEVKJYRZMIA-UHFFFAOYSA-M checkY
  • InChI=1/HI.Tl/h1H;/q;+1/p-1
    Key: CMJCEVKJYRZMIA-REWHXWOFAG
  • I[Tl]
Properties
TlI
Molar mass 331.287 g/mol[1]
Appearance yellow crystals[1]
Density 7.1 g/cm3[1]
Melting point 441.7 °C (827.1 °F; 714.8 K)[1]
Boiling point 824 °C (1,515 °F; 1,097 K)[1]
0.085 g/L (25 °C)[1]
Solubility insoluble in alcohol[1]
−82.2·10−6 cm3/mol[2]
Hazards
GHS labelling:
GHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
Danger
H300, H330, H373, H411
P260, P264, P270, P271, P273, P284, P301+P310, P304+P340, P310, P314, P320, P321, P330, P391, P403+P233, P405, P501
Flash point Non-flammable
Related compounds
Other anions
 Thallium(I) fluoride
Thallium(I) chloride
Thallium(I) bromide
Other cations
Gallium(I) iodide
Indium(I) iodide
Related compounds
 Mercury(II) iodide
Lead(II) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Thallium(I) iodide is a

AgI, CuI, SnI2, SnI4, PbI2 and HgI2
.

Chemistry

TlI can be formed in aqueous solution by metathesis of any soluble thallium salt with iodide ion. It is also formed as a by-product in thallium-promoted iodination of phenols with thallium(I) acetate.

Attempts to oxidise TlI to thallium(III) iodide fail, since oxidation produces thallium(I) triiodide, Tl+I3−.

Physical properties

The room temperature form of TlI is yellow and has an

rocksalt structure.[6]

Applications

Thallium(I) iodide was initially added to mercury arc lamps to improve their performance[7] The light produced was mainly in the blue green part of the visible light spectrum least absorbed by water, so these have been used for underwater lighting.[8] In modern times, it is added to quartz and ceramic metal halide lamps that uses rare-earth halides like dysprosium, to increase their efficiency and to get the light color more close to the blackbody locus. Thallium iodide alone can be used to produces green colored metal halide lamps. Thallium(I) iodide is also used in trace amounts with NaI or CsI to produce scintillators used in radiation detectors.

Natural occurrence

Natural thallium(I) iodide was first discovered in a naturally occurring setting in 2017 as a orthorhombic polymorph called nataliyamalikite. Small grains were found embedded in mascagnite sourced from fumaroles at Avachinsky, a volcano in Russia's Kamchatka Peninsula that can reach temperatures of 640 °C (1,184 °F). The geologists that discovered it speculate that further research into this mineral is likely to add to the understanding of the geochemical evolution of the planet[9][10]

Safety

Like all thallium compounds, thallium(I) iodide is highly toxic.

References

  1. ^ a b c d e f g Haynes, p. 4.94
  2. ^ Haynes, p. 4.136
  3. ^
    doi:10.1063/1.1678917
    .
  4. doi:10.1002/ejic.200600975
    .
  5. doi:10.1016/j.physb.2008.10.002
    .
  6. doi:10.1107/S0365110X51001641
    .
  7. doi:10.1364/JOSA.54.000532
    .
  8. ^ Underwater Journal and information bulletin, IPC Science and Technology Press, (1973), p 245
  9. ^ "Nataliyamalikite: Mineral information, data and localities". www.mindat.org.
  10. ^ Anderson, Natali (July 6, 2017). "New Mineral Discovered: Nataliyamalikite". Sci News. Retrieved March 16, 2022.

Cited sources
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