Question

Choose the order of splitting of complex having same metal atom/ion and ligands.

• A. Octahedral complex > Tetrahedral complex > Square planar complex
• B. Octahedral complex < Tetrahedral complex < Square planar complex
• C. Tetrahedral complex < Octahedral complex < Square planar complex
• D. Tetrahedral complex > Square planar complex > Octahedral complex

Answer 1

The correct option is C Tetrahedral complex < Octahedral complex < Square planar complex

Octahedral splitting is more compared to tetrahedral because there are 6 ligands in octahedral and they have higher electrostatic interaction with the metal ion/atom and result in higher splitting.

The square planar arrangement of ligands is derived from octahedral ligand field by removing two trans ligands located along the z-axis. Thus, lower of energy of $d_{x}z$ and $d_{y}z$ due to less ligand interaction with these. As the result the spilliting of d-orbital increases.
${\Delta }_s>1.3{\Delta }_o$

Hence, the correct order is
Octahedral complex < Tetrahedral complex < Square planar complex