Which one of the following will not show geometrical isomerism?

Options

A. (a) `[Cr(NH_3)_4Cl_2]Cl`
B. (b) `[Co(en)_2Cl_2]Cl`
C. (c) `[Co(NH_3)_5NO_2]Cl_2`
D. (d) `[Pt(NH_3)_2Cl_2]`

Explanation

To determine which coordination compound will not show geometrical isomerism, we need to analyze the types of coordination complexes and their geometries.

### Step-by-Step Solution:

1. **Understanding Geometrical Isomerism**:
Geometrical isomerism occurs in coordination compounds when there are different spatial arrangements of ligands around the central metal atom. This is typically seen in complexes with coordination numbers 4 and 6.

2. **Identify Coordination Numbers**:
- Coordination number 4 can lead to square planar or tetrahedral geometries.
- Coordination number 6 typically leads to octahedral geometry.

3. **Types of Coordination Complexes**:
- **M, A4, B2 type**: This indicates a coordination number of 6 with 4 identical ligands (A) and 2 identical ligands (B). This can show geometrical isomerism.
- **M, A2, B2 type**: This also indicates a coordination number of 4 with 2 A and 2 B ligands. This can show geometrical isomerism as well.
- **M, A5, B type**: This indicates a coordination number of 6 with 5 identical ligands (A) and 1 different ligand (B). This typically does not show geometrical isomerism because there is no alternative arrangement for the single different ligand.

4. **Analyzing the Given Options**:
- For **A4B2** and **A2B2** types, geometrical isomerism is possible due to different arrangements of the ligands.
- For **A5B** type, there is only one way to arrange the ligands around the central metal atom, which means it does not exhibit geometrical isomerism.

5. **Conclusion**:
The coordination compound that will not show geometrical isomerism is of the type **A5B**.

### Final Answer:
The coordination compound of type **A5B** will not show geometrical isomerism.

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