Explain `sp^(3)` d hybridisation with a suitable example.

Explanation

(i) In the `PCl_(5)` molecule, the central atom phosphorous is covalently bonded to five chlorine atoms. Here the atomic of phosphorous undergoes `sp^(3) d^(2)` hybridisation which involves its one 3s orbital, three 3p orbitals and one vacant 3d orbital `(d_(z)^(2)).`
(ii) The ground state electronic configuration of phosphorous is `[Ne]3s^(2)" "3p_(x)^(2)" "3p_(y)^(1)" "3p_(z)^(1)`

(iii) One of the paired electrons in the 3s orbital of f phosphorous is promoted to one of its vacant 3d orbital `(dz^(2))` in the excited state.

(iv) The `3p_(z)` orbitals of the five chlorine atoms inearly overlap along the axis with the five `sp_(3)` d hybridised orbitals of phosphorous to form the five `P - Cl sigma` bonds as follows.