Английская Википедия:Chromium(III) fluoride

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Шаблон:Chembox

Chromium(III) fluoride is an inorganic compound with the chemical formula Шаблон:Chem2. It forms several hydrates. The compound Шаблон:Chem2 is a green crystalline solid that is insoluble in common solvents, but the hydrates Шаблон:Chem2 (violet) and Шаблон:Chem2 (green) are soluble in water. The anhydrous form sublimes at 1100–1200 °C.[1]

Structures

Like almost all compounds of chromium(III), these compounds feature octahedral Cr centres. In the anhydrous form, the six coordination sites are occupied by fluoride ligands that bridge to adjacent Cr centres. In the hydrates, some or all of the fluoride ligands are replaced by water.[2]

Production

Chromium(III) fluoride is produced from the reaction of chromium(III) oxide and hydrofluoric acid:[3]

Шаблон:Chem2

The anhydrous form is produced from hydrogen fluoride and chromic chloride:[4]

Шаблон:Chem2

Another method of synthesis of Шаблон:Chem2 involves thermal decomposition of Шаблон:Chem2 (ammonium hexafluorochromate(III)):

Шаблон:Chem2

A mixed valence compound Шаблон:Chem2 (chromium(II,III) fluoride) is also known.[5]

Uses

Chromium(III) fluoride finds some applications as a mordant in textiles and as a corrosion inhibitor. Chromium(III) fluoride catalyzes the fluorination of chlorocarbons by HF.[6][7]

References

  1. Шаблон:Greenwood&Earnshaw2nd
  2. F.H. Herbstein, M. Kapon and G.M. Reisner, "Crystal structures of chromium(III) fluoride trihydrate. Structural chemistry of hydrated transition metal fluorides. Thermal decomposition of chromium(III) fluoride nonhydrate" Zeitschrift für Kristallographie 1985, volume 171, pp. 209
  3. Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger, "Chromium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.Шаблон:Doi
  4. Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. Шаблон:ISBN.
  5. Sturm. B.J. Phase Equilibria in the System Chromium(II)Fluoride-Chromium(III) Fluoride. Inorg. Chem., 1962, 1 (3), pp 665–672
  6. Mallikarjuna R. V. N.; Subramanian M. A. Fluoroolefin Manufacturing U.S. Patent 6,031,14, August 6, 1998; n.a.
  7. Ruh R. P.; Davis R. A. Proceess for Fluorinating Aliphatic Halohydrocarbons with a Chromium Fluoride catalyst and process for preparing the catalyst. U.S. Patent 2,745,886, May 15, 1956; n.a.

Шаблон:Chromium compounds Шаблон:Fluorides