Interhalogen compounds and ions

Lower valent states of iodine and chlorine in the presence of one another should generate interhalogen compounds and ions such as IC1,12C1 etc. These species, and polyanions such as IJ, should be considered in a more detailed mechanism... 

The halogens form many compounds and ions that are binary or ternary combinations of halogen atoms. There are three basic types (a) neutral interhalogen compounds, (b) interhalogen cations, and (c) interhalogen anions. 

One of the focal points of this work was the influence of traces of moisture on the cationic polymerization of epoxides. Using the previously described iodonium salt as an example, it was shown that water not only played an important role as co-catalyst in the photochemical formation of the superacid, but it also caused the hydrolysis of the iodonium salt via a nucleophihc attack at the T center. This reaction was mainly investigated by X-ray photoelectron spectroscopy (XPS). Interestingly, this hydrolysis only occurs with the hexafluoroantimonate salt and not with the corresponding chloride. Here it should be mentioned that the chloride salt resembles an interhalogen compound and the hexafluoroantimonate salt forms a real ion pair. Hydrolysis of the hexafluoroantimonate anion of the iodonium salt was not observed, but slow hydrolysis was observed for sodium hexafluoroantimonate. The hydrolysis is so slow overall that the influence of this effect can be excluded from the discussions into the influences of water and alcohol on the cationic polymerization of epoxides. 

The reactions of the interhalogen compounds are not greatly different from those of the halogens themselves. Hydrolysis of compounds in basic solution yield the halide ion derived from the smaller halogen and an oxy-halogen anion derived from the larger halogen thus, hydrolysis of BrF yields a 5 1 mixture of fluoride and bromate, Iodine monochloride... 

For xenon fluorides and oxides, for example, the same models can be apphed as for interhalogen and halogen oxy species. Furthermore, the very successful valence shell electron pair repulsion (VSEPR) rules for molecule and ion shapes are as effective for noble gas compounds and their relatives as for classical octet compounds. 

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