Question

Which of the following molecules has pentagonal bipyramidal shape?

• A. $P{{F}_{5}}$
• B. $S{{F}_{6}}$
• C. $Xe{{F}_{6}}$
• D. ${{[Fe{{(CN)}_{6}}]}^{3-}}$

Answer 1

Answer: (C)

$Xe{{F}_{6}}$

Answer 2

In the formation of $XeF _{6}$ molecule, three $5 p$ electrons are promoted to $5 d$ orbitals. Now, one 5s, three $5 p$ and three $5 d$ orbitals of Xe atom intermix together and form seven $s p^{3} d^{3}$ hybrid orbitals. One sp ${ }^{3} d^{3}$ hybrid orbital contains one lone pair of electrons while other six are half-filled. The expected geometry is pentagonal bipyramidal.