Which of the following will not show geometrical isomerism ?

Options

A. `[Cr(NH_(3))_(4) Cl_(2)]Cl`
B. `[Co(en)_(2) Cl_(2) ] Cl`
C. `[Co(NH_(3))_(5) NO_(2)]Cl_(2)`
D. `[Pt(NH_(3))_(2) Cl_(2)`

Explanation

To determine which of the given coordination compounds will not show geometrical isomerism, we need to analyze each option based on the presence of ligands.

### Step-by-Step Solution:

1. **Understanding Geometrical Isomerism**:
- Geometrical isomerism occurs in coordination compounds that have at least two ligands of the same type. The two common forms of geometrical isomerism are cis and trans.
- **Cis isomer**: Same type of ligands are on the same side.
- **Trans isomer**: Same type of ligands are on opposite sides.

2. **Analyzing the First Option: Cr(NH3)4Cl2Cl**:
- This compound has 4 NH3 ligands and 2 Cl ligands.
- Since there are two Cl ligands, this compound can show geometrical isomerism (both cis and trans forms are possible).

3. **Analyzing the Second Option: Co(en)2Cl2**:
- Here, "en" stands for ethylenediamine, which is a bidentate ligand. There are 2 "en" ligands and 2 Cl ligands.
- The presence of 2 Cl ligands allows for cis and trans isomers, thus this compound can show geometrical isomerism.

4. **Analyzing the Third Option: Co(NH3)5(NO2)Cl2**:
- In this compound, there are 5 NH3 ligands, 1 NO2 ligand, and 2 Cl ligands.
- However, since there is only one NO2 ligand and the other five ligands are the same (NH3), there are not two ligands of the same type that can create cis or trans isomers.
- Therefore, this compound cannot show geometrical isomerism.

5. **Conclusion**:
- Based on the analysis, the compound that will not show geometrical isomerism is **Co(NH3)5(NO2)Cl2** (Option C).

### Final Answer:
**Option C: Co(NH3)5(NO2)Cl2 will not show geometrical isomerism.**