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Two ways to find hybridization in complex compound -:

1- Valence bond theory

2- Crystal field theory

Valence bond Theory

The central metal cation or atom makes available a number of vacant s, p and or d-orbitals equal to its coordination number to form coordinate covalent bonds with ligands.

2. These vacant atomic orbitals of metal are hybridised to form a new set of equivalent bonding orbitals, called hybrid orbitals . These orbitals have the same geometry, the same energy and definite directional properties.

3. The bonding in metal complexes arises when a filled ligand orbital containing a lone pair of electrons overlaps a vacant hybrid orbital on the metal cation or atom to form a coordinate covalent bond.

4. Each ligand has at least one orbital containing a lone pair of electrons. Pauling classified the ligands into two categories (i) Strong ligands like CN ^– , CO ^– etc. (ii) weak ligands like F ^– , Cl ^– etc.

5. Strong ligands have a tendency to pair up the d-electrons of a metal cation or atom to provide the necessary orbitals for hybridization. On the other hand, weak ligands do not have a tendency to pair up the d-electrons.

6. The d orbital used in hybridization may be either inner (n-1) d-orbitals or outer n d-orbitals . The complex formed by inner (n-1) d-orbitals, is called inner orbital complex whereas the complex formed by outer d-orbital is called outer orbital complex .

7. If unpaired electrons are present within the complex, then complex is paramagnetic in nature while if all the electrons are paired then complex is diamagnetic in nature.

Limitations

• It could not explain the nature of ligands.
• It could not explain why the pairing of electrons occurs in the presence of strong ligands.
• It could not explain the colour and electronic spectra of complexes.
• It could not explain reaction rates and the mechanism of reactions of complexes.
• This theory does not provide any quantitative interpretation data about the thermodynamic and kinetic stability of coordination complexes.

It's very hard to explain this complicated thing in writing form so you better find some YouTube video to learn hybridization of coordination compounds.

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