Thallium halides
The thallium halides include monohalides, where thallium has oxidation state +1, trihalides, where thallium generally has oxidation state +3, and some intermediate halides containing thallium with mixed +1 and +3 oxidation states. X is a halogen. These salts find use in specialized optical settings, such as focusing elements in research spectrophotometers. Compared to the more common zinc selenide-based optics, materials such as thallium bromoiodide enable transmission at longer wavelengths. In the infrared, this allows for measurements as low as 350 cm−1, whereas zinc selenide is opaque by 21.5 μm, and zinc sulfide optics are generally only usable to 650 cm−1.
Monohalides
The monohalides, also known as thallous halides, all contain thallium with oxidation state +1. Parallels can be drawn between the thallium halides and their corresponding silver salts; for example, thallium chloride and bromide are light-sensitive, and thallium fluoride is more soluble in water than the chloride and bromide.;Thallium fluoride
;Thallium chloride
;Thallium bromide
;Thallium iodide
Thallium(I) mixed halides
Thallium bromoiodide or thallium bromide iodide and thallium bromochloride or thallium bromide chloride are mixed salts of thallium that are used in spectroscopy as an optical material for transmission, refraction, and focusing of infrared radiation. The materials were first grown by R. Koops in the laboratory of Olexander Smakula at the Carl Zeiss Optical Works, Jena in 1941. The red bromoiodide was coded KRS-5 and the colourless bromochloride, KRS-6 and this is how they are commonly known. The KRS prefix is an abbreviation of "Kristalle aus dem Schmelz-fluss",. The compositions of KRS-5 and KRS-6 approximate to and. KRS-5 is the most commonly used, its properties of being relatively insoluble in water and non-hygroscopic, make it an alternative to KBr, CsI, and AgCl.Trihalides
The thallium trihalides, also known as thallic halides, are less stable than their corresponding aluminium, gallium, and indium counterparts and chemically quite distinct. The triiodide does not contain thallium with oxidation state +3 but is a thallium compound and contains the linear ion.[Thallium(III) fluoride]
Thallium(III) chloride
Thallium(III) bromide
Thallium(I) triiodide">Thallium triiodide">Thallium(I) triiodide
Mixed-valence halides
As a group, these are not well characterised. They contain both Tl and Tl, where the thallium atom is present as complex anions, e.g..;;
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Halide complexes
;Thallium complexes;Thallium fluoride complexes
;Thallium chloride complexes
;Thallium bromide complexes
;Thallium iodide complexes
Further information
Category:Metal halidesCategory:Mixed valence compounds
Category:Thallium compounds