The crystal field stabilization energy (CFSE) is the highest for

Options

A. `[CoF_(4)]^(2-)`
B. `[Co(NCS)_(4)]^(2-)`
C. `[Co(NH_(3))_(6)]^(3+)`
D. `[CoCl_(4)]^(2-)`

Explanation

To determine which coordination complex has the highest crystal field stabilization energy (CFSE), we need to analyze the relationship between CFSE, ligand strength, and coordination number.

### Step-by-Step Solution:

1. **Understanding CFSE**:
- CFSE is the energy difference between the energy of the electrons in a crystal field and the energy of the electrons in a spherical field. It is influenced by the geometry of the complex and the nature of the ligands.

2. **Coordination Number and Geometry**:
- Coordination number refers to the number of ligand atoms that are bonded to the central metal atom. The most common coordination numbers are 4 and 6.
- For coordination number 4, the complexes can be tetrahedral or square planar. Tetrahedral complexes generally have lower CFSE compared to octahedral complexes.
- For coordination number 6, the geometry is octahedral, which typically has a higher CFSE due to the greater splitting of d-orbitals.

3. **Ligand Strength**:
- The strength of the ligands also plays a crucial role in determining CFSE. Strong field ligands lead to greater splitting of d-orbitals and thus higher CFSE.

4. **Comparing Options**:
- If we consider the options given:
- Options with coordination number 4 (tetrahedral or square planar) will have lower CFSE.
- The option with coordination number 6 (octahedral) will have a higher CFSE due to the larger splitting of d-orbitals.

5. **Conclusion**:
- Therefore, the crystal field stabilization energy (CFSE) is the highest for the coordination number 6 complex, which is typically octahedral.

### Final Answer:
The crystal field stabilization energy (CFSE) is the highest for the coordination number 6 complex (octahedral complex).

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