Geometrical isomerism can be shown by

Options

A. `[Ag(CN)(NH_(3))]`
B. `Na_(2)[Cd(NO_(2))_(4)]`
C. `[PtCl_(4)I_(2)]^(-2)`
D. `[PtCl(NH_(3))_(3)][Au(CN)_(4)]`

Answer

To determine which complexes can exhibit geometrical isomerism, we need to analyze each option provided in the question. Geometrical isomerism typically occurs in coordination compounds where the arrangement of ligands around a central metal atom can lead to different spatial configurations.

### Step-by-Step Solution:

1. **Understanding Geometrical Isomerism**:
- Geometrical isomerism arises when ligands can be arranged in different spatial orientations around a central atom. The most common types are cis (same side) and trans (opposite sides).

2. **Analyzing Option 1: M-AB**:
- In this case, M-AB indicates a complex with one metal atom (M) and two different ligands (A and B).
- Since there are only two ligands, they can only be arranged in one way, meaning there is no possibility for cis/trans arrangements.
- **Conclusion**: This option cannot exhibit geometrical isomerism.

3. **Analyzing Option 2: MA4**:
- Here, MA4 indicates a complex with one metal atom (M) and four identical ligands (A).
- Since all ligands are the same, there is no variation in arrangement; hence, geometrical isomerism cannot occur.
- **Conclusion**: This option cannot exhibit geometrical isomerism.

4. **Analyzing Option 3: MA4B2**:
- This complex has one metal atom (M), four identical ligands (A), and two different ligands (B).
- The arrangement of the two B ligands can lead to different configurations. For example, if the two B ligands are adjacent, it forms a cis isomer, while if they are opposite each other, it forms a trans isomer.
- **Conclusion**: This option can exhibit geometrical isomerism.

5. **Analyzing Option 4: MA2B2**:
- In this case, there are two identical ligands (A) and two identical ligands (B).
- Similar to the previous case, the arrangement of A and B can lead to cis and trans configurations.
- **Conclusion**: This option can also exhibit geometrical isomerism.

### Final Conclusion:
- The complexes that can exhibit geometrical isomerism are **Option 3 (MA4B2)** and **Option 4 (MA2B2)**.