With interhalogens fluorides

Only four interhaiogens with the formula XY5 or XY7 are known (Table VI). Synthesis involves direct fluorination of the element or a lower interhalogen fluoride. Fluorination of appropriate metal salts may also be employed. 

Because of the size of the iodine atom and the fact that it is easier to oxidize to the +7 state, IF7 is the only XX 7 interhalogen. It is prepared by the reaction of IF5 and F2 at elevated temperatures, and like other halogen fluorides it is a strong fluorinating agent. When it reacts with water, HF and HI04 are produced. 

Many of the reactions that xenon fluorides undergo are similar in some ways to those of interhalogens. However, the xenon halides differ markedly in terms of their reactivity, with XF2 being much less reactive than either XeF4 or XeF6. The difluoride reacts only slowly with water,... 

Fluorine also reacts with other halogens, forming interhalogen compounds. While with bromine and iodine it reacts vigorously at ordinary temperatures, with chlorine the reaction occurs at 200°C. Such interhalogen products with these halogens include iodine heptafluoride, bromine trifluoride, bromine pentafluoride, and chlorine trifluoride. Metalloid elements, such as arsenic, silicon, selenium, and boron also inflame in a stream of fluorine, forming fluorides. 

Metal salts are generally converted to the metal fluorides by reactions with the halogen fluorides, with the metal being oxidized to its highest oxidation state if an excess of the interhalogen is present. 

In Chapter 16, several reactions of interhalogens were shown in which cations were produced by a reaction with a strong fluoride ion acceptor (Lewis acid). One reaction of this type is the following ... 

In chemical behavior similar to that of interhalogens, the xenon fluorides act as fluorinating agents in a wide variety of reactions. Xenon difluoride is a milder reagent than is the tetrafluoride or the hexafluoride. It readily reacts with olefins to add fluorine ... 

The compound BrF can be prepared by fluorinating bromine not with elemental fluorine but with a higher bromine fluoride in a disproportionation reaction (equations 33 and 34). Fluorination of halides (equation 35) instead of elemental halogen is sometimes preferable, leading to purer products. Interhalogen compounds also include astatine ones such as AtCl, AtBr, and Atl. 

On the basis of self-ionic dissociation, these compounds can be prepared by acid-base reactions. Heteropolyhalogen cations are usually prepared by reacting the parent compound with a Lewis acid (equation 51) in which XY = interhalogen and MYm = Lewis acid, for example, hahdes of B, Al, P, As, and Sb, and so on (equations 52 and 53). Such reactions can be performed by direct interaction of the reactants with an excess of the more volatile reactant, which can then be pumped off, after completion of the reaction, leaving behind the pure product. Sometimes it is preferable to perform such reactions in solution, such as in anhydrous hydrogen fluoride (AHF), and pump off the solvent at the end of the reaction. 

Boron trifluoride forms addition compounds that incorporate an sp hybridized boron into a tetravalent structure. Salts of BF4 are readily formed with BF3 and a suitable fluoride donor. Halogen fluorides such as chlorine trifluoride react with BF3 to generate interhalogen cations such as [C1F2]+[BF4]. Some further examples are shown in equations (43) and (44). In an organic application, the Schiemann reaction provides an entry into fluorinated aromatics by thermal decomposition of a diazonimn tetrafluoroborate (equation 45). 

Violent reactions with ammonium salts, chlorate salts, beryllium fluoride, boron diiodophosphide, carbon tetrachloride + methanol, 1,1,1-trichloroethane, 1,2-dibromoethane, halogens or interhalogens (e.g., fluorine, chlorine, bromine, iodine vapor, chlorine trifluoride, iodine heptafluoride), hydrogen iodide, metal oxides + heat (e.g., beryllium oxide, cadmium oxide, copper oxide, mercury oxide, molybdenum oxide, tin oxide, zinc oxide), nitrogen (when ignited), silicon dioxide powder + heat, polytetrafluoroethylene powder + heat. 

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