Q. What are Hexahalides?

Hexahalides: S, Se-and Te react with excess of fluorine to give the corresponding hexafluorides. Fluorine being the most electronegative oxidises the other elements to their highest oxidation states. Therefore, hexahalides other than fluorides are not formed. In hexafluorides the central atom uses its d-orbitals for bonding. The structure of SF₆ can be explained on the basis of sp³d² hybridisation as shown below:

The sp³d²hybridisation gives rise to a symmetrical structure with fluorine atoms octahedrally arranged around the hexavalent sulphur as shown in Fig. 9.13. The other hexafluorides also have similar structures.

While SF₆, and SeF₆, are quite inactive; TeF₆, gets slowly hydrolysed in the presence or water.

Te₆ + 6H₂O ---------------------à 6HF + H₆ TeO₆