Question

The transition metal complex(es) with zero magnetic moment, zero dipole moment and CFSE of –2.4 \( \Delta_o \) is(are)

• A. \([ \text{Mn(CO)}_5 ] \)
• B. \([ \text{trans}-\text{Ni}(\text{ethylene diamine})_2\text{Cl}_2 ] \)
• C. \([ \text{trans}-\text{Co(CN)}_4(\text{H}_2\text{O})]^{2-} \)
• D. \([ \text{trans-Fe(CN)}_4\text{Cl}_4]^{3-} \)

Hint:

For zero magnetic moment and dipole moment, look for low-spin, symmetric complexes with appropriate electron configurations.

Answer 1

The Correct Option is C, D

Step 1: Analyzing the properties.
- Zero magnetic moment: A zero magnetic moment indicates that all electrons are paired, which is typical of a low-spin complex.
- Zero dipole moment: This suggests that the complex is symmetric in structure.
- CFSE (Crystal Field Stabilization Energy) of –2.4 \( \Delta_o \) indicates a specific electronic arrangement in the ligand field.

Step 2: Analyzing the options.
- Option (D) \([ \text{trans-Fe(CN)}_4\text{Cl}_4]^{3-} \) has a low-spin configuration with paired electrons, a symmetric arrangement, and a CFSE of –2.4 \( \Delta_o \), which satisfies all the given conditions.
- Other options do not meet the criteria for zero magnetic moment and the required CFSE.

Step 3: Conclusion.
The correct complex is (D).