Question

On the basis of valence bond theory, explain the nature of bonding in the [Ni(Cl)₄]²⁻ complex ion.

Answer 1

1. Oxidation state of nickel is +2.
2. Valence shell electronic configuration of Ni²⁺
   
3. The number of Cl⁻ ligands is 4. Therefore, the number of vacant metal ion orbitals required for bonding with ligands must be four.
4. Four orbitals on metal available for hybridisation are one 4s and three 4p. The complex is tetrahedral.
   
   The four metal ion orbitals for bonding with Cl⁻ ligands are derived from the sp³ hybridisation.
5. Four vacant sp³ hybrid orbitals of Ni²⁺ overlap with four orbitals of Cl⁻ ions.
6. Configuration after complex formation would be
   
7. The complex has two unpaired electrons and hence is paramagnetic.