Question

Give a valence bond description of the bonding in the high spin complex [MnCl₆]³⁻ Include orbital diagram for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding. Specify the number of unpaired electrons.

Answer 1

[MnCl₆]³⁻ (High spin)

1. Oxidation state of manganese = + 3, Mn³⁺
   Electron configuration of Mn³⁺ : [Ar] 3d⁴
   Orbital diagram of free metal ion:
   
2. Because the complex is high spin, pairing of electrons will not occur. So in the complex orbital diagram of Mn³⁺ will remain the same.
   ∴ d ²sp³ hybridization is not possible. Hence, one 4s, three 4p and two 4d orbitals hybridize to give six sp³d ² vacant hybrid orbitals.
3. The six vacant hybrid orbitals of Mn³⁺ overlap with six filled orbitals of six ligands forming Mn → Cl coordinate bonds.
   
4. There are 4 unpaired electrons in the complex