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

Concept: Crystal Field Theory (CFT) explains the properties of coordination compounds by considering the interaction between the central metal ion and surrounding ligands as purely electrostatic in nature. According to this theory, ligands are regarded as point charges (for anions) or point dipoles (for neutral molecules), and the metal-ligand bond is assumed to be ionic.

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. \[ \boxed{\text{Statement (A) is correct}} \]

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. \[ \boxed{\text{Statement (B) is incorrect}} \]

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. \[ \boxed{\text{Statement (C) is incorrect}} \]

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

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