Chlorine monofluoride is a volatile interhalogen compound with the chemical formula . It is a colourless gas at room temperature and is stable even at high temperatures. When cooled to −100 °C, ClF condenses as a pale yellow liquid. Many of its properties are intermediate between its parent halogens, chlorine| and fluorine|.

Geometry

The molecular structure in the gas phase was determined by microwave spectroscopy; the bond length is r<sub>e</sub>&nbsp;= 1.628341(4)&nbsp;Å.

The bond length in the crystalline ClF is 1.628(1)&nbsp;Å; the lengthening relative to the free molecule is due to an interaction of the type F-Br···ClMe with a distance of 2.640(1)&nbsp;Å. In its molecular packing it shows very short intermolecular Cl···Cl contacts of 3.070(1)&nbsp;Å between neighboring molecules.

Reactivity

Chlorine monofluoride is a versatile fluorinating agent, converting metals and non-metals to their fluorides and releasing in the process. For example, it converts tungsten to tungsten hexafluoride and selenium to selenium tetrafluoride:

:

:

FCl can also chlorofluorinate compounds, either by addition across a multiple bond or via oxidation. For example, it adds fluorine and chlorine to the carbon of carbon monoxide, yielding carbonyl chloride fluoride COClF, an intermediate between phosgene and carbonyl fluoride.

:CO + ClF → class=skin-invert-image|50px

Safety

Chlorine monofluoride is extremely reactive. It instantly destroys glass and ignites organic material on contact, reacts violently with water, is highly corrosive to mucous membranes and the skin, eyes, and respiratory tract, and may cause permanent blindness.

See also

  • Chlorine fluorides
  • Oxygen monofluoride

References

  • National Pollutant Inventory - Fluoride and compounds fact sheet
  • WebBook page for FCl