Question #8855a

According to the chemistry textbook "Inorganic Chemistry" by Holleman-Wiberg, 2001, p. 527, sulfur hexabromide (#"SBr"_6#) does not exist. However, sulfur hexafluoride (#"SF"_6"#) does exist, so this answer will pertain to sulfur hexafluoride.

Normally we think of only unpaired valence electrons as bonding electrons, and the paired electrons as non-bonding electrons, However, electron orbitals can hybridize, forming hybridized orbitals from the s, p, and d orbitals.

In the case of sulfur hexabromide (#"SF"_6"#), the six valence electrons in the sulfur atom hybridize to form six sp3d2 orbitals, each with the same energy, and each capable of forming a bond with a bromine atom.

fig 1.27- Formation of #"SF"_6# molecule involving sp3d2 Hybridization

To account for the hexavalency in #"SF"_6#, one electron each from the 3s and 3p orbitals is promoted to 3d orbitals as shown in fig.1.27(b).

These six orbitals get hybridised to form six sp3d2 hybrid orbitals. The name sp3d2 comes from the fact that the hybridized orbital comes from 1 s orbital, 3 p orbitals, and 2 d orbitals.

Each of these sp3d2 hybrid orbitals overlaps with a 2p orbital of a fluorine atom to form a S-F bond.
http://www.tutorvista.com/content/chemistry/chemistry-iv/atomic-structure/sp3d2-hybridization.php

The six sp3d2 orbitals are at right angles to one another, and the molecule will have an octahedral shape.