Chromium pentafluoride

Chromium pentafluoride
Names

IUPAC name Chromium(V) fluoride
Other names Chromium fluoride, Chromium(V) fluoride, Pentafluorochromium, Pentafluoridochromium
Identifiers
CAS Number	14884-42-5
3D model (JSmol)	Interactive image
ChemSpider	4574207
PubChem CID	5460742
InChI InChI=1S/Cr.5FH/h;5*1H/q+5;;;;;/p-5 Key: OMKYWARVLGERCK-UHFFFAOYSA-I
SMILES F[Cr](F)(F)(F)F
Properties^[1]
Chemical formula	CrF₅
Molar mass	146.988 g/mol
Appearance	red crystals
Density	2.89 g/cm³
Melting point	34 °C (93 °F; 307 K)
Boiling point	117 °C (243 °F; 390 K)
Structure^[2]
Crystal structure	orthorhombic
Space group	Pbcm, No. 57
Lattice constant	a = 782.9 pm, b = 753.4 pm, c = 551.8 pm
Formula units (Z)	4
Coordination geometry	octahedral
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemical compound

Chromium pentafluoride is the inorganic compound with the chemical formula CrF₅.^[3] It is a red volatile solid that melts at 34 °C.^[1] It is the highest known chromium fluoride, since the hypothetical chromium hexafluoride has not yet been synthesized.^[4]

Chromium pentafluoride is one of the products of the action of fluorine on a mixture of potassium and chromic chlorides.^[5]

In terms of its structure, the compound is a one-dimensional coordination polymer. Each Cr(V) center has octahedral molecular geometry.^[2] It has the same crystal structure as vanadium pentafluoride.^[6]

Chromium pentafluoride is strongly oxidizing, able to fluorinate the noble gas xenon and oxidize dioxygen to dioxygenyl.^[2] Due to this property, it decomposes readily in the presence of reducing agents, and easily hydrolyses to chromium(III) and chromium(VI).^[7]

Reactions

Chromium pentafluoride can react with Lewis bases such as caesium fluoride and nitryl fluoride to give the respective hexafluorochromate(V) salt.^[8]

CrF₅ + CsF → CsCrF₆

Chromium pentafluoride can also react with the Lewis acid antimony pentafluoride to give the CrF₅·2SbF₅ adduct. The adduct was found to be a strong oxidizing agent, liquid at room temperature with a melting point of −23 °C.^[8]

References

^ ^a ^b Perry, Dale L. (2011). Handbook of Inorganic Compounds, Second Edition. Boca Raton, Florida: CRC Press. p. 125. ISBN 978-1-43981462-8. Retrieved 2014-01-10.
^ ^a ^b ^c Shorafa, H.; Seppelt, K. (2009). "The structures of CrF₅ and CrF₅*SbF₅". Zeitschrift für anorganische und allgemeine Chemie. 635 (1): 112–114. doi:10.1002/zaac.200800378.
^ Jacques Guertin; James A. Jacobs; Cynthia P. Avakian, eds. (2004). Chromium(VI) Handbook. CRC Press. p. 30. ISBN 9780203487969.
^ 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.
^ A. G. Sharpe (2012). J.H. Simons (ed.). Fluorine Chemistry. Vol. 2. Elsevier. p. 24. ISBN 9780323145435.
^ A. G. Sharpe (1983). Advances in Inorganic Chemistry. Vol. 27. Academic Press. p. 103. ISBN 9780080578767.
^ Amit Aora (2005). Text Book Of Inorganic Chemistry. Discovery Publishing House. p. 649.
^ ^a ^b Brown, S. D.; Loehr, T. M.; Gard, G. L. (1976). "The Chemistry of chromium pentafluoride II. Reaction with inorganic systems". Journal of Fluorine Chemistry. 7 (1): 19–32. doi:10.1016/S0022-1139(00)83979-2. ISSN 0022-1139.