Question

‘X’ is the number of electrons in $ t_2g $ orbitals of the most stable complex ion among $ [Fe(NH_3)_6]^{3+} $, $ [Fe(Cl)_6]^{3-} $, $ [Fe(C_2O_4)_3]^{3-} $ and $ [Fe(H_2O)_6]^{3+} $. The nature of oxide of vanadium of the type $ V_2O_x $ is: 
 

• A. Acidic
• B. Neutral
• C. Basic
• D. Amphoteric

Hint:

The stability of a complex ion depends on the ligand field and the metal ion's charge. The presence of strong ligands, like oxalate, increases the stability of the complex.

Answer 1

The Correct Option is D

This question requires analyzing the provided coordination complexes to determine the electron count in the \( t_{2g} \) orbitals of the most stable complex ion.

The given complexes are analyzed as follows:

1. \([Fe(NH_3)_6]^{3+}\):
   • Ligand: Ammonia (\( NH_3 \)) is a strong field ligand.
   • Iron oxidation state: \( +3 \).
   • \( Fe^{3+} \) electronic configuration: \( [Ar] \, 3d^5 \).
   • Strong field ligands induce d-orbital splitting (\( t_{2g} \) and \( e_g \)) and electron pairing.
   • The \( t_{2g} \) orbitals are filled before \( e_g \). In this case, 4 electrons occupy the \( t_{2g} \) orbitals.
2. \([Fe(Cl)_6]^{3-}\):
   • Ligand: Chloride (\( Cl^- \)) is a weak field ligand.
   • Iron oxidation state: \( +3 \).
   • \( Fe^{3+} \) electronic configuration: \( [Ar] \, 3d^5 \).
   • Weak field ligands do not cause electron pairing.
3. \([Fe(C_2O_4)_3]^{3-}\):
   • Ligand: Oxalate (\( C_2O_4^{2-} \)) is a strong field ligand.
   • Iron oxidation state: \( +3 \).
   • \( Fe^{3+} \) electronic configuration: \( [Ar] \, 3d^5 \).
   • Electron pairing occurs with strong field ligands.
4. \([Fe(H_2O)_6]^{3+}\):
   • Ligand: Water (\( H_2O \)) is a weak field ligand.
   • Iron oxidation state: \( +3 \).
   • \( Fe^{3+} \) electronic configuration: \( [Ar] \, 3d^5 \).
   • No electron pairing occurs.

Based on the analysis, \( [Fe(C_2O_4)_3]^{3-} \) is the most stable complex due to the maximum electron occupation in the \( t_{2g} \) orbitals, resulting in a \( t_{2g}^5 \) configuration.

The second part of the question concerns the nature of the vanadium oxide \( V_2O_x \).

Vanadium exhibits multiple oxidation states, leading to various oxides:

• For \( x=5 \) in \( V_2O_5 \), the oxide is amphoteric, exhibiting both acidic and basic properties.

The nature of this oxide is Amphoteric.