Interhalogen

In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms (fluorine, chlorine, bromine, iodine, or astatine) and no atoms of elements from any other group.

Most interhalogen compounds known are binary (composed of only two distinct elements). Their formulae are generally XYn, where n = 1, 3, 5 or 7, and X is the less electronegative of the two halogens. The value of n in interhalogens is always odd, because of the odd valence of halogens. They are all prone to hydrolysis, and ionize to give rise to polyhalogen ions. Those formed with astatine have a very short half-life due to astatine being intensely radioactive.

No interhalogen compounds containing three or more different halogens are definitely known,[1] although a few books claim that IFCl2 and IF2Cl have been obtained,[2][3][4][5] and theoretical studies seem to indicate that some compounds in the series BrClF
n are barely stable.[6]

Some interhalogens, such as BrF3, IF5, and ICl, are good halogenating agents. BrF5 is too reactive to generate fluorine. Beyond that, iodine monochloride has several applications, including helping to measure the saturation of fats and oils, and as a catalyst for some reactions. A number of interhalogens, including IF7, are used to form polyhalides.[1]

Similar compounds exist with various pseudohalogens, such as the halogen azides (FN3, ClN3, BrN3, and IN3) and cyanogen halides (FCN, ClCN, BrCN, and ICN).

  1. ^ a b Cite error: The named reference Chemistry of Interhalogens was invoked but never defined (see the help page).
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 824. ISBN 978-0-08-037941-8.
  3. ^ Cite error: The named reference Meyers was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Murthy was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Sahoo was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Ignatiev was invoked but never defined (see the help page).