Which of the following pairs of structures represents facial and meridional isomers resectively ?

Options

A.
B.
C.
D.

Answer

To solve the question regarding facial and meridional isomers, we need to understand the definitions and characteristics of these isomers in coordination chemistry. Here’s a step-by-step solution:

### Step 1: Understand the Definitions
- **Facial Isomer**: In a facial isomer, three identical ligands occupy one face of the octahedral complex. This means that the three ligands are adjacent to each other.
- **Meridional Isomer**: In a meridional isomer, three identical ligands occupy a plane that divides the octahedral complex into two halves. This means that the three ligands are arranged in a way that they form a "meridian" across the octahedron.

### Step 2: Identify the Coordination Complex
The coordination complex given in the question is [Co(NH3)3Cl3]. This complex has cobalt (Co) as the central metal ion, three ammonia (NH3) ligands, and three chloride (Cl) ligands.

### Step 3: Draw the Facial Isomer
For the facial isomer, we can arrange the ligands such that the three NH3 ligands are on one face of the octahedron. This can be visualized as follows:
- Place the Co at the center.
- Position the three NH3 ligands on one face, and the three Cl ligands on the opposite face.

### Step 4: Draw the Meridional Isomer
For the meridional isomer, we arrange the ligands such that the three NH3 ligands are in a plane that divides the octahedron. This can be visualized as follows:
- Again, place the Co at the center.
- Position the three NH3 ligands in a way that they form a straight line across the octahedron, with one Cl ligand on either side.

### Step 5: Compare the Structures
Now, we need to compare the drawn structures of the facial and meridional isomers to identify which pairs represent these isomers.

### Step 6: Identify the Correct Option
From the options provided, we need to find the pair that shows the facial isomer first and the meridional isomer second.

After analyzing the drawn structures:
- The first option represents the facial isomer.
- The second option represents the meridional isomer.

Thus, the correct answer is the first option.

### Final Answer
The correct pair of structures that represents facial and meridional isomers respectively is **Option 1**.

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