Difference between revisions of "Oxygen difluoride"

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'''Oxygen difluoride''', OF<sub>2</sub>, sometimes known as '''difluorine monoxide''',{{#tag:ref|Fluorine is more [[Electronegativity|electronegative]] than oxygen, both on the normal numerical scales<ref>{{Allred (1961)}}.</ref> and on the conventional series used in inorganic nomenclature,<ref>{{RedBook2005|page=260}}.</ref> so OF<sub>2</sub> is usually considered a fluoride of oxygen and not an oxide of fluorine. However, other X<sub>2</sub>O compounds (X&nbsp;= Cl, Br) are considered to be halogen oxides, and so F<sub>2</sub>O is sometimes considered to be a member of this series, dispite its somewhat different chemistry.<ref name="C&W">{{Cotton&Wilkinson5th|pages=454–56}}.</ref>|group=note}} is the most stable of the binary compounds of [[oxygen]] and [[fluorine]].<ref name="G&E"/><ref name="C&W"/> It was discovered as a byproduct of fluorine production using [[Moissan cell]]s ([[electrolysis]] of [[Hydrogen fluoride|HF]]/[[Potassium fluoride|KF]]) due to small amounts of water in the electrolyte.<ref>{{citation | last1 = Lebeau | first1 = P. | last2 = Damiens | first2 = A. | title = Sur l'existence d'un composé oxygéné du fluor | journal = C. R. Hebd. Acad. Sci. Paris | year = 1927 | volume = 185 | pages = 652–54 | url = http://gallica.bnf.fr/ark:/12148/bpt6k31384/f652.image}}.</ref> 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.<ref>{{citation | last1 = Lebeau | first1 = P. | last2 = Damiens | first2 = A. | title = Sur un nouveau mode de préparation du fluorure d'oxygène | journal = C. R. Hebd. Acad. Sci. Paris | year = 1929 | volume = 188 | pages = 1253–55 | url = http://gallica.bnf.fr/ark:/12148/bpt6k31417/f1253.image}}.</ref><ref>{{citation | last = Yost | first = D. M. | title = Oxygen Fluoride | journal = Inorg. Synth. | year = 1939 | volume = 1 | pages = 109–11}}.</ref><ref>{{citation | title = Concerning the mechanism of formation of oxygen difluoride | first1 = Evan H. | last1 = Appelman | first2 = Albert W. | last2 = Jache | journal = J. Am. Chem. Soc. | year = 1987 | volume = 109 | issue = 6 | pages = 1754–57 | doi = 10.1021/ja00240a026}}.</ref>
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'''Oxygen difluoride''', OF<sub>2</sub>, sometimes known as '''difluorine monoxide''',{{#tag:ref|Fluorine is more [[Electronegativity|electronegative]] than oxygen, both on the normal numerical scales<ref>{{Allred (1961)}}.</ref> and on the conventional series used in inorganic nomenclature,<ref>{{RedBook2005|page=260}}.</ref> so OF<sub>2</sub> is usually considered a fluoride of oxygen and not an oxide of fluorine. However, other X<sub>2</sub>O compounds (X&nbsp;= Cl, Br) are considered to be halogen oxides, and so F<sub>2</sub>O is sometimes considered to be a member of this series, despite its somewhat different chemistry.<ref name="C&W">{{Cotton&Wilkinson5th|pages=454–56}}.</ref>|group=note}} is the most stable of the binary compounds of [[oxygen]] and [[fluorine]].<ref name="G&E"/><ref name="C&W"/> It was discovered as a byproduct of fluorine production using [[Moissan cell]]s ([[electrolysis]] of [[Hydrogen fluoride|HF]]/[[Potassium fluoride|KF]]) due to small amounts of water in the electrolyte.<ref>{{citation | last1 = Lebeau | first1 = P. | last2 = Damiens | first2 = A. | title = Sur l'existence d'un composé oxygéné du fluor | journal = C. R. Hebd. Acad. Sci. Paris | year = 1927 | volume = 185 | pages = 652–54 | url = http://gallica.bnf.fr/ark:/12148/bpt6k31384/f652.image}}.</ref> 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.<ref>{{citation | last1 = Lebeau | first1 = P. | last2 = Damiens | first2 = A. | title = Sur un nouveau mode de préparation du fluorure d'oxygène | journal = C. R. Hebd. Acad. Sci. Paris | year = 1929 | volume = 188 | pages = 1253–55 | url = http://gallica.bnf.fr/ark:/12148/bpt6k31417/f1253.image}}.</ref><ref>{{citation | last = Yost | first = D. M. | title = Oxygen Fluoride | journal = Inorg. Synth. | year = 1939 | volume = 1 | pages = 109–11}}.</ref><ref>{{citation | title = Concerning the mechanism of formation of oxygen difluoride | first1 = Evan H. | last1 = Appelman | first2 = Albert W. | last2 = Jache | journal = J. Am. Chem. Soc. | year = 1987 | volume = 109 | issue = 6 | pages = 1754–57 | doi = 10.1021/ja00240a026}}.</ref>
  
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==Structure==
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Oxygen difluoride has a bent ''C''<sub>2v</sub> structure as expected by [[VSEPR theory]]. The oxygen–fluorine bond length is 140.5&nbsp;pm and the bond angle at oxygen is 103°, consistent with single bonding and sp<sup>3</sup> hybridization at oxygen.<ref name="G&E"/><ref name="C&W"/>
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{| class=wikitable
 +
|-
 +
! &nbsp;
 +
! ''r''(O–X)/pm
 +
! X–O–X/°
 +
! &nbsp;
 +
! &nbsp;
 +
! ''r''(O–X)/pm
 +
! X–O–X/°
 +
|-
 +
| [[Oxygen difluoride|OF<sub>2</sub>]]
 +
| 140.5
 +
| 103
 +
| &nbsp;
 +
| [[Oxygen difluoride|F<sub>2</sub>O]]
 +
| 140.5
 +
| 103
 +
|-
 +
| [[Hypofluorous acid|HOF]]
 +
| 144.2 (O–F)<br/>96.4 (O–H)
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| 97
 +
| &nbsp;
 +
| [[Dichlorine monoxide|Cl<sub>2</sub>O]]
 +
|
 +
|
 +
|-
 +
| [[Water|H<sub>2</sub>O]]
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| 95.7
 +
| 104.5
 +
| &nbsp;
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| [[Dibromine monoxide|Br<sub>2</sub>O]]
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|
 +
|
 +
|-
 +
|}
 
==Notes and references==
 
==Notes and references==
 
===Notes===
 
===Notes===

Revision as of 15:23, 31 December 2010

Oxygen difluoride
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 compounds Dioxygen difluoride
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
H2O 95.7 104.5   Br2O

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.

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