Oxygen difluoride

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Oxygen difluoride
IUPAC name Oxygen difluoride
Other names Difluorine monoxide
Difluorooxidane
Difluoridooxygen
Identifiers
InChI InChI=1/F2O/c1-3-2
InChIKey UJMWVICAENGCRF-UHFFFAOYAI
Standard InChI InChI=1S/F2O/c1-3-2
Standard InChIKey UJMWVICAENGCRF-UHFFFAOYSA-N
CAS number [7783-41-7]
EC number 231-996-7
ChemSpider 22593
Properties[1][2][3]
Chemical formula OF2
Molar mass 55.996 g mol−1
Appearance colourless gas
Density 1.90 g cm−3 (liquid, −223.8 °C)
Melting point

−223.8 °C (49.4 K)

Boiling point

−145.3 °C (127.9 K)

Thermochemistry[4]
Std enthalpy of formation ΔfHo298 +24.52 kJ mol−1
Standard molar entropy So298 247.46 J K−1 mol−1
Related compounds
Other fluorides of oxygen Dioxygen difluoride
Other compounds Dichlorine monoxide
Dibromine monoxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Oxygen difluoride, OF2, sometimes known as difluorine monoxide,[note 1] is the most stable of the binary compounds of oxygen and fluorine.[1][7] It was discovered as a byproduct of fluorine production using Moissan cells (electrolysis of HF/KF) due to small amounts of water in the electrolyte.[8] A more satisfactory method of preparation is the reaction of fluorine with 2% aqueous sodium hydroxide solution followed by fractional distillation of the gas produced.[9][10][11]

Structure

Oxygen difluoride has a bent C2v structure as expected by VSEPR theory. The oxygen–fluorine bond length is 140.5 pm and the bond angle at oxygen is 103°, consistent with single bonding and sp3 hybridization at oxygen.[1][7]

  r(O–X)/pm X–O–X/°     r(O–X)/pm X–O–X/°
OF2 140.5 103   F2O 140.5 103
HOF 144.2 (O–F)
96.4 (O–H)
97   Cl2O 170.0 110.9
H2O 95.7 104.5   Br2O 184.3 112.2

Notes and references

Notes

  1. Fluorine is more electronegative than oxygen, both on the normal numerical scales[5] and on the conventional series used in inorganic nomenclature,[6] so OF2 is usually considered a fluoride of oxygen and not an oxide of fluorine. However, other X2O compounds (X = Cl, Br) are considered to be halogen oxides, and so F2O is sometimes considered to be a member of this series, despite its somewhat different chemistry.[7]

References

  1. 1.0 1.1 1.2 Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 748–49. ISBN 0-08-022057-6.
  2. CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p B-126. ISBN 0-8493-0462-8.
  3. Streng, Alex G. Miscibility and Compatibility of Some Liquid and Solidified Gases at Low Temperature. J. Chem. Eng. Data 1971, 16 (3), 357–59. DOI: 10.1021/je60050a024.
  4. Difluorine monoxide. In NIST Chemistry WebBook; National Institute for Standards and Technology, <http://webbook.nist.gov/cgi/inchi/InChI%3D1S/F2O/c1-3-2>. (accessed 31 December 2010).
  5. Allred, A. L. Electronegativity values from thermochemical data. J. Inorg. Nucl. Chem. 1961, 17 (3–4), 215–21. DOI: 10.1016/0022-1902(61)80142-5.
  6. Nomenclature of Inorganic Chemistry; IUPAC Recommendations 2005; Royal Society of Chemistry: Cambridge, 2005; p 260. ISBN 0-85404-438-8, <http://www.iupac.org/publications/books/rbook/Red_Book_2005.pdf>.
  7. 7.0 7.1 7.2 Cotton, F. Albert; Wilkinson, Geoffrey Advanced Inorganic Chemistry, 5th ed.; Wiley-Interscience: New York, 1988; pp 454–56. ISBN 0-471-84997-9.
  8. Lebeau, P.; Damiens, A. Sur l'existence d'un composé oxygéné du fluor. C. R. Hebd. Acad. Sci. Paris 1927, 185, 652–54, <http://gallica.bnf.fr/ark:/12148/bpt6k31384/f652.image>.
  9. Lebeau, P.; Damiens, A. Sur un nouveau mode de préparation du fluorure d'oxygène. C. R. Hebd. Acad. Sci. Paris 1929, 188, 1253–55, <http://gallica.bnf.fr/ark:/12148/bpt6k31417/f1253.image>.
  10. Yost, D. M. Oxygen Fluoride. Inorg. Synth. 1939, 1, 109–11.
  11. Appelman, Evan H.; Jache, Albert W. Concerning the mechanism of formation of oxygen difluoride. J. Am. Chem. Soc. 1987, 109 (6), 1754–57. DOI: 10.1021/ja00240a026.

External links

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