Interhalogen compound

The shapes of interhalogen molecules such as CIF3, Brp5 and IF7 are largely in agreement with the predictions of VSEPR theory. The orbital lobes show nonbonding pairs of electrons. 

CIF3 is one of the most reactive of all chemical compounds, instantly setting fire to glass wool and asbestos. One drop of CIF3 sets fire to paper, cloth or wood, and the liquid reacts with water with a noise like the crack of a whip. 

A fair number of interhalogen compounds with the general formula XY where n = 1, 3, 5, or 7, are known, the more well-established ones being those listed in Table 7.1. 

A common reaction of the uncharged interhalogens is with powerful halide acceptors, resulting in interhalogen cations  

CIF3 -1-AsFj [C1F2+][AsF6 ] BrFj +2SbFs - [BrF4+][Sb2Fn IF7-I-BF3 - [IF6+][BF4-] 

Certain halogen fluorides also act as fluoride anion acceptors  

TABLE 7.1 A List of Relatively Stable Interhalogens Containing No More than Two Different Halogens 

Because the halogens exist as diatomic molecules, diatomic molecules made up of two different halogen atoms exist. These compounds are the simplest examples of interhalogens, compounds, such as GIF and IF5, formed between two halogen elements. 

The vast majority of the higher interhalogen compounds have a central Cl, Br, or I atom surrounded by fluorine atoms. The large size of the iodine atom allows the formation of IF3, IF5, and IF7, in which the oxidation state of I is 4-3, +5, and +7, respectively. 

The large volume of gases produced provides thrust 

Gutmann (ed.), MTP International Review of Science Inorganic Chemistry Series 1, Vol. 3, pp. 53-84, Butterworths, London, 1972. 

Christe, IUPAC Additional Publication 24th Int. Congr. Pure Appl. Chem., Hamburg, 1973, Vol. 4. Compounds of Non-Metals, pp. 115-41, Butterworths, London, 1974. 

All six possible diatomic compounds between F, Cl, Br and I are known. Indeed, ICl was first made (independently) by J. L. Gay Lussac and 

Davy in 1813-4 soon after the isolation of the parent halogens themselves, and its existence led J. von Liebig to miss the discovery of the new element bromine, which has similar properties (p. 794). The compounds vary considerably in thermal stability CIF is extremely robust ICl and IBr are moderately stable and can be obtained in very pure crystalline form at room temperature BrCl readily dissociates reversibly into its 

In general the compounds have properties intermediate between those of the parent halogens, though a combination of aggressive chemical reactivity and/or thermal instability militates against the determination of physical properties such as mp, bp, etc., in some instances. However, even for such highly dissociated species as BrCl, precise molecular (as distinct from bulk) properties can be determined by spectroscopic techniques. Table 17.12 summarizes some of the more important physical properties of the 

Form at room Colourless Pale brown Unstable Red brown Ruby red Black 

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INTER HALOGEN COMPOUNDS AND POLYHALIDES There are four types of interhalogen compound ... 

Sihcon and boron bum ia fluorine forming siUcon tetrafluoride [7783-61-17, SiF, and boron trifluoride [7637-07-2] respectively. Selenium and tellurium form hexafluorides, whereas phosphoms forms tri- or pentafluorides. Fluorine reacts with the other halogens to form eight interhalogen compounds (see Fluorine compounds, inorganic-halogens). 

J. E. Gall and co-workers, "Interhalogen Compounds of Fluorine," papers presented m Annual ACS Meeting, New York, Sept. 1947. 

J. E. Ellis and G. Iveson, The Application of Gas-Eiquid Chromatography to the Analysis of Volatile Halogen and Interhalogen Compounds, Gas Chromatography, Butterworths, London, 1956 pp. 300—309. 

The interhalogen compounds are the bromine- and iodine-base materials. It is the larger, more positive halogen that is the reactive portion of the interhalogen molecule during the disinfection process. Although only used on a limited basis at present, there are members of this class that show great promise as environmentally safe disinfectants. 

Two approaches that have been investigated recently for disinfection are mixtures of bromine and chlorine, and mixtures containing bromide or iodide salts. Some evidence exists that mixtures of bromine and chlorine have superior germicidal properties than either halogen alone. It is believed that the increased bacterial activity of these mixtures can be attributed to the attacks by bromine on sites other than those affected by chlorine. The oxidation of bromide or iodide salts can be used to prepare interhalogen compounds or the hypollalous acid in accordance with the following reaction ... 

Interhalogen compounds such as iodine monochloride have been added to fluoroalkyl-substituted alkenes. The observed unidirectional regiochemistry can be explained by the polarity ot the double bond [14] (equation 7)... 

Interhalogen compounds react withperfluoroalkylhydrides to yield mixtures of halosubstituted products [43] (equations 25 and 26)... 

Sei f-Test 2.4A Write the Lewis structure for the interhalogen compound chlorine... 

Interhalogen compounds are compounds of two different halogens that have, with few exceptions, the general formula XX . Examples include BrCI, C1F, and IF5. Use I ewis structures to explain why n is always an odd number. 

Of these, (a), (c), (d), and (e) can all function as greenhouse gases. 2.113 All halogens have an odd number of valence electrons (7). As a consequence interhalogen compounds of the type XX will be extremely reactive radicals unless the total number of halogens is an even number, which can only be achieved if n is odd. Look at IC12 vs. IC13 as examples ... 

In a series of seven recent publications, these Italian authors21-27 reported isobutylene homo- and copolymerizations using alkylaluminum coinitiators in the presence of halogen, interhalogen compounds and alkyl halide initiators. The following conclusions21 are reported in the first paper. 

C21-0093. Some pure liquid interhalogen compounds are good electrical conductors, indicating that they contain cations and anions. Show a Lewis acid-base reaction between two bromine trifluoride molecules that would generate ionic species. 

Interhalogen compounds, hardly surprisingly, add to alkenes very much as do the halogens themselves, and the following order of reactivity has been observed ... 

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