Question

What is the structure of `PCl_5`?

Answer 1

Well we got `5xx"P-Cl"` bonds.....

Explanation:

...the which are arranged as a trigonal bipyramid around the central phosphorus atom.

And thus `Cl_"equatorial"-P-Cl_"equatorial"=120^@`

And `Cl_"axial"-P-Cl_"axial"=180^@`

The equivalent structure, `PF_5`, provided a classic example of the conformational mobility of a five-coordinate centre....the axial and equatorial substituents can be interchanged by a low-energy mechanism...so called `"turnstile rotation"`, or `"Berry pseudorotation"`....