Which of the following complexes show linkage isomerism ?

Options

A. `[Co(NH_(3))_(5)(NO_(2))]^(2+)`
B. `[Co(H_(2)O)_(5)CO]^(3+)`
C. `[Cr(NH_(3))_(5)]SCN^(2+)`
D. `[Fe(en)_(2)Cl_(2)]^(+)`

Explanation

To determine which of the following complexes show linkage isomerism, we need to understand the concept of linkage isomerism and identify ambidentate ligands in the given complexes.

### Step-by-Step Solution:

1. **Understanding Linkage Isomerism**:
- Linkage isomerism occurs when a ligand can coordinate to the metal center through different atoms. This typically involves ambidentate ligands, which have more than one potential donor atom.

2. **Identifying Ambidentate Ligands**:
- Ambidentate ligands are those that can attach to the metal through different atoms. Common examples include ligands like NO2 (which can bind through nitrogen or oxygen) and SCN (which can bind through sulfur or nitrogen).

3. **Analyzing Each Complex**:
- **Complex 1: [Co(NH3)5(NO2)]**:
- The NO2 ligand can coordinate through nitrogen (N) or oxygen (O). Therefore, this complex can show linkage isomerism.

- **Complex 2: [Co(NH3)5(CO)]**:
- The CO ligand coordinates only through carbon (C) and does not have an alternative donor atom. Therefore, this complex does not show linkage isomerism.

- **Complex 3: [Cr(NH3)5(SCN)]**:
- The SCN ligand can coordinate through sulfur (S) or nitrogen (N). Thus, this complex can also show linkage isomerism.

- **Complex 4: [Co(NH3)5(EN)]**:
- The EN (ethylenediamine) ligand is a bidentate ligand but does not have multiple donor sites. Therefore, this complex does not show linkage isomerism.

4. **Conclusion**:
- The complexes that show linkage isomerism are:
- [Co(NH3)5(NO2)] (Complex 1)
- [Cr(NH3)5(SCN)] (Complex 3)

### Final Answer:
The complexes that show linkage isomerism are **Complex 1 and Complex 3**.

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