Chemistry:Chromium hexafluoride

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Chromium hexafluoride or chromium(VI) fluoride (CrF6) is a hypothetical chemical compound between chromium and fluorine with the chemical formula CrF6. It was previously thought to be an unstable yellow solid decomposing at −100 °C,[1] but this has been shown to be a misidentification of chromium pentafluoride, CrF5.[2]

Unsuccessful attempts at synthesis

CrF6 used to be thought to be produced by exhaustive fluorination of chromium metal at 400 °C and 20 MPa of pressure, and immediate freezing out of the reaction chamber to prevent decomposition:

Cr + 3 F2 → CrF6

However, it has been shown that chromium pentafluoride (CrF5) is formed instead:

2 Cr + 5 F2 → 2 CrF5

and that CrF6 has yet to be synthesized.

References

  1. Hope, Eric G.; Levason, William.; Ogden, J. Steven (1991). "Is chromium hexafluoride octahedral? Experiment still suggests "yes!"". Inorganic Chemistry 30 (26): 4873. doi:10.1021/ic00026a002. 
  2. Riedel, Sebastian; Kaupp, Martin (2009). "The highest oxidation states of the transition metal elements". Coordination Chemistry Reviews 253 (5–6): 606–624. doi:10.1016/j.ccr.2008.07.014. http://144.206.159.178/ft/243/588116/14862785.pdf.