Question

Choose the Incorrect option regarding valence bond theory of coordination compound.

• A. It does not give a quantitative interpretation of the thermodynamic stabilities of coordination compounds.
• B. It does not explain the colour exhibited by coordination compounds.
• C. It does not give quantitative interpretation of magnetic data.
• D. It does not distinguish between outer orbital and inner orbital complexes.

Hint:

A major success of VBT is the distinction between inner orbital complexes (\(d^2sp^3\)) and outer orbital complexes (\(sp^3d^2\)).

Answer 1

The Correct Option is D

Concept: Valence Bond Theory (VBT) was proposed to explain bonding in coordination compounds. Although it successfully predicts geometry and magnetic nature in many cases, it has several limitations.

Step 1: Recall the achievements of VBT.
VBT explains:
• Hybridisation of metal orbitals.
• Geometry of complexes.
• Inner orbital and outer orbital complexes.
• Approximate magnetic behaviour.

Step 2: Recall the limitations of VBT.
VBT fails to explain:
• Colour of coordination compounds.
• Thermodynamic stability quantitatively.
• Detailed magnetic data quantitatively.
• Spectral properties.

Step 3: Evaluate each statement.
Option (A): Correct limitation. Option (B): Correct limitation. Option (C): Correct limitation. Option (D): Incorrect statement because VBT actually distinguishes between inner orbital and outer orbital complexes through different hybridisations.

Step 4: Identify the incorrect option.
Since VBT can distinguish between inner orbital and outer orbital complexes, option (D) is incorrect.