Question

Select the correct assumptions in Crystal Field Theory (CFT) from the following: (A) Ligands are treated as point charge or point dipole. (B) The five \(d\) orbitals in an isolated gaseous metal atom are non-degenerate. (C) Degeneracy of the \(d\) orbitals is restored with the approach of ligand towards metal. (D) Metal-ligand bond is ionic arising purely from electrostatic interactions. Choose the correct answer from the options given below:

• A. (B) and (C) only
• B. (A) and (D) only
• C. (B), (C) and (D) only
• D. (A), (B) and (D) only

Hint:

Crystal Field Theory considers metal-ligand bonding as purely electrostatic and ignores covalent character. Ligand approach causes splitting of degenerate \(d\)-orbitals.

Answer 1

The Correct Option is B

Step 1: Examine statement (A).
In Crystal Field Theory, negatively charged ligands are treated as point charges and neutral ligands are treated as point dipoles. Therefore statement (A) is correct. \[ {\text{Statement (A) is correct}} \]

Step 2: Examine statement (B).
For an isolated gaseous metal atom or ion, all five \(d\)-orbitals possess the same energy. Thus they are degenerate. Statement (B) says that they are non-degenerate, which is incorrect. \[ {\text{Statement (B) is incorrect}} \]

Step 3: Examine statement (C).
When ligands approach the metal ion, the degeneracy of the \(d\)-orbitals is removed and splitting occurs. Therefore degeneracy is not restored; rather it is destroyed. Hence statement (C) is incorrect. \[ {\text{Statement (C) is incorrect}} \]

Step 4: Examine statement (D).
Crystal Field Theory assumes that metal-ligand bonding arises purely from electrostatic attraction. Therefore statement (D) is correct. \[ {\text{Statement (D) is correct}} \]

Step 5: Select the correct combination.
The correct assumptions are: \[ (A)\ \text{and}\ (D) \] Hence the correct answer is: \[ {(A)\ \text{and}\ (D)\ \text{only}} \]