`underset([Co(en)_(2)ClBr]NO_(2))(X) to "Isomer"`
`A overset(AgNO_(3))to "Yellow ppt" `
`B overset(AgNO_(3)) to "White ppt"`
C- exhibit facial meridional.
how many structures C have?

Options

A. 2
B. 3
C. 1
D. 4

Answer

To solve the question regarding the coordination compound \([Co(en)_2ClBr]NO_2\) and its isomers, we will follow these steps:

### Step 1: Identify the Isomers
We have a coordination compound \([Co(en)_2ClBr]NO_2\). The compound has two isomers, A and B, based on the reaction with silver nitrate (\(AgNO_3\)).

### Step 2: Analyze the Precipitate Formation
- **Isomer A** reacts with \(AgNO_3\) to form a **yellow precipitate**. The yellow precipitate indicates the presence of bromide ions (\(Br^-\)), suggesting that \(Br\) is outside the coordination sphere.
- **Isomer B** reacts with \(AgNO_3\) to form a **white precipitate**. The white precipitate indicates the presence of chloride ions (\(Cl^-\)), suggesting that \(Cl\) is outside the coordination sphere.

### Step 3: Determine the Coordination Sphere
From the above analysis:
- For **Isomer A**: The coordination sphere is \([Co(en)_2Cl]^{+}\) with \(Br\) and \(NO_2^-\) outside.
- For **Isomer B**: The coordination sphere is \([Co(en)_2Br]^{+}\) with \(Cl\) and \(NO_2^-\) outside.

### Step 4: Identify the Structures of Isomer C
Isomer C is formed from both Isomer A and Isomer B. We need to determine how many structures C can have, considering that it exhibits facial and meridional isomerism.

### Step 5: Check for Facial and Meridional Isomerism
Facial (fac) and meridional (mer) isomerism occurs in octahedral complexes with the general formula \(MA_3B_3\). In our case, we have:
- \(A\) = \(en\) (bidentate ligand)
- \(B\) = \(Cl\) or \(Br\) (monodentate ligands)

Since we have two bidentate ligands and two different monodentate ligands, we do not meet the criteria for \(MA_3B_3\) complexes. Therefore, Isomer C does not exhibit facial or meridional isomerism.

### Step 6: Count the Structures
- For **Isomer A**, we have one structure of C.
- For **Isomer B**, we also have one structure of C.

Thus, the total number of structures C is:
\[ 1 + 1 = 2 \]

### Conclusion
The total number of structures C that can be formed is **2**.

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