Number of possible isomer for the complex `[Co(en)_(2)CI_(2)]CI` will be: (em = ethylenediamine)

Options

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

Explanation

To determine the number of possible isomers for the complex \([Co(en)_2Cl_2]Cl\), we can follow these steps:

### Step 1: Identify the Coordination Number
The coordination number of cobalt in this complex is 6. This is because ethylenediamine (en) is a bidentate ligand, meaning it can form two bonds with the cobalt atom. Since there are two ethylenediamine ligands and two chloride ligands, the total coordination number is \(2 \times 2 + 2 = 6\).

**Hint:** Remember that the coordination number is the total number of bonds formed between the metal and the ligands.

### Step 2: Determine the Geometry
With a coordination number of 6, the geometry of the complex is octahedral. In an octahedral geometry, there are different arrangements of the ligands around the central metal atom.

**Hint:** Visualize the octahedral shape and consider how ligands can be arranged in space.

### Step 3: Draw Possible Isomers
1. **Cis Isomer:** In the cis isomer, the two chloride ligands are adjacent to each other. The structure can be represented as:
- Cl
- Co
- Cl
- en
- en

2. **Trans Isomer:** In the trans isomer, the two chloride ligands are opposite each other. The structure can be represented as:
- Cl
- Co
- en
- en
- Cl

**Hint:** Use a diagram to visualize the arrangement of ligands in both cis and trans forms.

### Step 4: Check for Optical Isomerism
Next, we need to check if any of these isomers exhibit optical isomerism (chirality):
- **Cis Isomer:** The cis isomer has a plane of symmetry and is not optically active.
- **Trans Isomer:** The trans isomer also has a plane of symmetry and is not optically active.

Since both the cis and trans forms do not exhibit optical activity, we need to consider the possibility of optical isomers.

**Hint:** Look for any asymmetry in the arrangement of ligands to determine optical activity.

### Step 5: Count the Isomers
From the analysis:
- We have 1 cis isomer (not optically active).
- We have 1 trans isomer (not optically active).

Thus, the total number of possible isomers for the complex \([Co(en)_2Cl_2]Cl\) is **2**.

**Final Answer:** The number of possible isomers for the complex \([Co(en)_2Cl_2]Cl\) is **2**.