Which of the following ions favour square planar geometry ?

Options

A. `Au^(+3)`
B. `Ir^(+)`
C. `Pt^(+2)`
D. `Ag^(+2)`

Answer

To determine which ions favor square planar geometry, we need to identify the ions that exhibit dsp² hybridization. Square planar geometry is typically associated with transition metal complexes where the central metal ion has a coordination number of 4 and utilizes dsp² hybridization.

### Step-by-Step Solution:

1. **Understanding Square Planar Geometry**:
- Square planar geometry is characterized by a coordination number of 4.
- The hybridization involved in square planar complexes is dsp².

2. **Identifying the Ions**:
- We will analyze the electronic configurations of the given ions to determine if they can exhibit dsp² hybridization.

3. **Analyzing Au³⁺ (Gold)**:
- The electronic configuration of Au is [Xe] 4f¹⁴ 5d¹⁰ 6s¹.
- For Au³⁺, we remove 3 electrons: 1 from 6s and 2 from 5d.
- This gives us the configuration: [Xe] 4f¹⁴ 5d⁸.
- In the presence of strong field ligands, the d electrons can pair up, allowing for dsp² hybridization.
- **Conclusion**: Au³⁺ favors square planar geometry.

4. **Analyzing Ir³⁺ (Iridium)**:
- The electronic configuration of Ir is [Xe] 4f¹⁴ 5d⁷ 6s².
- For Ir³⁺, we remove 3 electrons: 2 from 6s and 1 from 5d.
- This gives us the configuration: [Xe] 4f¹⁴ 5d⁷.
- Similar to Au³⁺, strong field ligands can cause pairing in the d orbitals, leading to dsp² hybridization.
- **Conclusion**: Ir³⁺ favors square planar geometry.

5. **Analyzing Pt²⁺ (Platinum)**:
- The electronic configuration of Pt is [Xe] 4f¹⁴ 5d⁹ 6s¹.
- For Pt²⁺, we remove 2 electrons: 1 from 6s and 1 from 5d.
- This gives us the configuration: [Xe] 4f¹⁴ 5d⁸.
- Again, strong field ligands can lead to pairing in the d orbitals, allowing for dsp² hybridization.
- **Conclusion**: Pt²⁺ favors square planar geometry.

6. **Analyzing Ag²⁺ (Silver)**:
- The electronic configuration of Ag is [Kr] 4d¹⁰ 5s¹.
- For Ag²⁺, we remove 2 electrons: 1 from 5s and 1 from 4d.
- This gives us the configuration: [Kr] 4d⁹.
- Ag²⁺ does not exhibit dsp² hybridization; instead, it typically shows sp³ hybridization.
- **Conclusion**: Ag²⁺ does not favor square planar geometry.

### Final Answer:
The ions that favor square planar geometry are Au³⁺, Ir³⁺, and Pt²⁺.

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