Question

The complex with the highest magnitude of crystal field splitting energy (\(\Delta_0\)) is:

• A. \( [Cr(OH_2)_6]^{3+} \)
• B. \( [Ti(OH_2)_6]^{3+} \)
• C. \( [Fe(OH_2)_6]^{3+} \)
• D. \( [Mn(OH_2)_6]^{3+} \)

Hint:

For transition metals, a higher oxidation state and stronger ligand field lead to a greater \(\Delta_0\).

Answer 1

The Correct Option is A

Step 1: Factors Affecting Crystal Field Splitting
The magnitude of \(\Delta_0\) depends on the oxidation state, metal size, and ligand type.
Higher oxidation states lead to stronger field splitting.
Step 2: Comparing the Ions
\( Cr^{3+} \) has a smaller ionic radius than \( Mn^{3+} \), \( Fe^{3+} \), and \( Ti^{3+} \).
Smaller cations have a stronger ligand interaction, increasing \(\Delta_0\).
Final Answer: The complex \( [Cr(OH)_6]^{3+} \) has the highest crystal field splitting energy.

Answer 2

The complex with the highest magnitude of crystal field splitting energy (\(\Delta_0\)) is \( [Cr(H_2O)_6]^{3+} \).

Explanation:
- Crystal field splitting energy (\(\Delta_0\)) depends on the metal ion's charge, the nature of the ligands, and the metal's position in the periodic table.
- \( [Cr(H_2O)_6]^{3+} \) has chromium in the +3 oxidation state, which means a higher positive charge compared to similar complexes with lower oxidation states.
- A higher positive charge on the metal ion leads to a stronger attraction between the metal ion and the ligands, causing greater splitting of the d-orbitals.
- Water is a moderate field ligand, and the \( +3 \) charge on chromium significantly increases the crystal field splitting.
- Thus, among the common aqua complexes, \( [Cr(H_2O)_6]^{3+} \) exhibits the highest \(\Delta_0\) value.