Question

For the complex ion of ${{[Co{{(N{{H}_{3}})}_{6}}]}^{3+}}$.
(i) State the hybridisation of the complex.
(ii) State the magnetic nature of the complex.

Answer 1

You should know that the complex given in the question is an inner orbital complex and the ammonia group present is a strong field ligand. So, figure out which orbitals are involved by this ligand and you will know about the hybridisation of the complex.

Complete step by step solution:
Given that,
A complex ion is having a chemical formula ${{[Co{{(N{{H}_{3}})}_{6}}]}^{3+}}$ and we have to find out the hybridisation and the magnetic nature of the complex.
We should know that the complex ion given in the question has a total oxidation state of $+3$. In the complex ion, the cobalt is bound to six molecules of ammonia. The oxidation state of ammonia here is $0$.
Let us consider the oxidation state of cobalt to be X.
And, the oxidation state of the complex will be $X\times 1+6\times 0=+3$.
So, the oxidation state of cobalt will be $X=+3$.
We know that the electronic configuration of cobalt is $[Ar]3{{d}^{7}}4{{s}^{2}}$.
So, in cobalt with oxidation state three, two electrons will be extracted from the s-orbital and one electron will be removed from the d- orbital. Thus, the electronic configuration of cobalt having oxidation state will be $[Ar]3{{d}^{6}}$.
As ammonia is a strong field ligand, it will pair up the four unpaired electrons present in the d-orbital of cobalt and will free up the two $3d$ orbitals (thus, cobalt will not have any unpaired electrons). These $3d$ orbitals are involved in the hybridisation with one $4s$, three $4p$ orbitals forming an inner orbital complex.
So, the hybridisation of ${{[Co{{(N{{H}_{3}})}_{6}}]}^{3+}}$ will be ${{d}^{2}}s{{p}^{3}}$.
As it has no unpaired electrons, the complex will be diamagnetic in nature.

Note: It is important to note that, diamagnetic materials usually repel from magnetic substances and there is no permanent net magnetic moment per atom as all the electrons present are only paired electrons.