Stability of the complex depends on

Options

A. Oxidation state
B. Nature of ligand
C. Geometry of complex
D. All of these

Answer

To determine the factors affecting the stability of coordination complexes, we can analyze the following key aspects:

### Step-by-Step Solution:

1. **Oxidation State**:
- The stability of a coordination complex is influenced by the oxidation state of the metal ion. Generally, as the oxidation state of the metal increases, the stability of the complex also increases. This is because a higher positive charge on the metal ion enhances its ability to attract and hold onto the ligands, leading to a more stable complex.

2. **Nature of Ligand**:
- The type of ligands attached to the metal ion plays a crucial role in the stability of the complex. Ligands can be classified as strong or weak field ligands. Strong field ligands (like CN⁻, CO) lead to greater splitting of the d-orbitals and result in more stable complexes due to stronger metal-ligand interactions. Conversely, weak field ligands (like I⁻, Br⁻) result in less splitting and thus lower stability.

3. **Geometry of the Complex**:
- The spatial arrangement of ligands around the central metal ion, known as the geometry of the complex, also affects stability. Different geometries (such as octahedral, tetrahedral, or square planar) have different stability profiles. For example, square planar complexes are often more stable than octahedral or tetrahedral complexes for certain metal ions, particularly for d8 metal ions like Ni²⁺ and Pt²⁺.

4. **Crystal Field Splitting Energy (Δ)**:
- The stability of a complex can also be analyzed in terms of crystal field splitting energy (Δ). A larger Δ indicates a greater energy difference between the split d-orbitals, which can lead to increased stability, especially in strong field ligands.

### Conclusion:
In summary, the stability of coordination complexes depends on:
- The oxidation state of the metal ion.
- The nature of the ligands (strong vs. weak).
- The geometry of the complex.
- The crystal field splitting energy.