Question

Why are the axial bonds in pcl5 longer than equatorial bonds?

Answer 1

In PCl5, there are three equatorial bonds and two axial bonds. The axial bonds are longer than equatorial bonds because of greater repulsion from equatorial bonds. The 2-axial bonds are at 90º degree angle to 3-equatorial bonds while all equatorial bond are at 120º angle to each other. So axial bonds are nearer to equatorial bonds and this causes greater repulsion resulting elongation of bond length.

Answer 2

In PCl5 (Structure Shown In The Picture),

There are 3 equitorial bond in the same plane at the angle of 120° from each other and,

2 axial bonds which are at the angle of 180° .......

This is observed that the axial bonds are longer than the equatorial bonds due to repulsion between axial and equitorial bond..