In $PCl _{5}$, phosphorus shows $s p^{3} d$ hybridisation. It forms 5 equivalent $s p^{3} d$ orbitals. The structure of $PCl _{5}$ is trigonal bipyramidal in which three chlorine atoms are at the corners of triangle while two chlorine atoms are at axial position.
Bond length of axial bond is greater than the length of equatorial bond to minimise the bond pair-bond pair repulsion between axial and equatorial bonds.
