The number of possible isomers of a square planar complex, [mabcd] is/are

Options

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

Answer

To determine the number of possible isomers for the square planar complex [MABCD], we need to analyze the arrangement of the ligands around the central metal atom (M).

### Step-by-Step Solution:

1. **Identify the Complex**:
The complex is [MABCD], where M is the central metal atom and A, B, C, D are the ligands.

2. **Understand Square Planar Geometry**:
In a square planar complex, the ligands are arranged at the corners of a square around the central metal atom. This means that the arrangement of the ligands can lead to different isomers based on their positions.

3. **Count the Ligands**:
We have four different ligands: A, B, C, and D. Since they are all different, we can consider the different arrangements of these ligands.

4. **Determine Possible Arrangements**:
For square planar complexes, the isomerism can arise from the different ways the ligands can be arranged. The key arrangements to consider are:
- A and B can occupy adjacent positions, while C and D occupy the other two positions.
- A and C can occupy adjacent positions, while B and D occupy the other two positions.
- A and D can occupy adjacent positions, while B and C occupy the other two positions.

5. **List the Isomers**:
- Isomer 1: A and B adjacent, C and D adjacent.
- Isomer 2: A and C adjacent, B and D adjacent.
- Isomer 3: A and D adjacent, B and C adjacent.

6. **Count the Isomers**:
After analyzing the arrangements, we find that there are a total of 3 distinct isomers for the square planar complex [MABCD].

### Conclusion:
The total number of possible isomers of the square planar complex [MABCD] is **3**.