Chromium(II) chloride

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Chromium(II) chloride
IUPAC name	Chromium(II) chloride
Other names	Chromous chloride
Identifiers
CAS number	[10049-05-5]
Properties
Molecular formula	CrCl₂
Molar mass	122.92 g/mol
Melting point	824°C
Boiling point	1120°C
Hazards
MSDS	Oxford MSDS
EU classification	Harmful
Related compounds
Other cations	Chromium(III) chloride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Chromium(II) chloride is the chemical compound with the formula Cr Cl₂. This white, crystalline solid is used for the synthesis of other chromium complexes. CrCl₂ is hygroscopic. It dissolves in water to give bright blue solutions that are easily oxidized by air to give Cr(III)-containing products. CrCl₂ crystallizes in the cadmium chloride motif.

1 Synthesis
2 Uses
3 References
4 External links

[edit] Synthesis

CrCl₂ is produced by reducing chromium(III) chloride with hydrogen at 500 °C:^[1]

CrCl₃ + 1/2H₂ → CrCl₂ + HCl

Small scale preparations can use LiAlH₄, or related reagents, to reduce CrCl₃

4 CrCl₃ + LiAlH₄ → 4 CrCl₂ + LiCl + AlCl₃ + 2 H₂

Commonly, it is generated in situ by reduction of CrCl₃ with zinc.

[edit] Uses

Chromium(II) chloride is used as precursor to other inorganic and organometallic chromium complexes. Alkyl halides and nitroaromatics are reduced by CrCl₂. The moderate electronegativity of chromium and the range of substrates that CrCl₂ can accommodate make organochromium reagents very synthetically versatile.^[2] it is a reagent in the Nozaki-Hiyama-Kishi reaction.

[edit] References

Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

^ Burg, A. B.. "Anhydrous Chromium(II) Chloride". Inorg. Synth. 3: 150-153. doi:10.1002/9780470132340.
^ Kazuhiko Takai, K.; Loh, T.-P. "Chromium(II) Chloride" in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons: New York; 2005. DOI: 10.1002/047084289X.rc166.