Interhalogen ions

These ions have the general formulas XY+ and XY , where n can be 2, 4, 5, 6, and 8, and the central halogen X is usually heavier than Y. Table 17.2.2 lists many of the known interhalogen ions. 

Anions BrClj cucr CIF4 i2ci3- IFf- ClFg IF8  

The structures of these ions normally conform to those predicted by the VSEPR theory, as shown in Fig. 17.2.2. Since the anion XY has two more electrons than the cation XY+, they have very different shapes. The anion IFj- is planar with lone pairs occupying the axial positions of a pentagonal bipyramid. In [Me4N](IF6), IFg is a distorted octahedron (C3V symmetry) with a sterically active lone pair, whereas both BrFg and ClFg are octahedral. The anion IF has the expected square antiprismatic structure. 

Structures of some interhalogen ions. The number of electrons in the valence shell of the central atom is given for each ion. 

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The structures reported in this Group are divided equally into oxo- or thio-ionic species and interhalogen ions. 

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