The number of possible isomers of an octahedral complex `[Co(C_(2)O_(4))_(2)(NH_(3))_(2)]^-` is

Options

A. a. 1
B. b. 2
C. c. 3
D. d. 4

Explanation

To determine the number of possible isomers of the octahedral complex \([Co(C_2O_4)_2(NH_3)_2]^-\), we will analyze the ligands and their arrangements.

### Step-by-Step Solution:

1. **Identify the Ligands**:
The complex consists of two types of ligands: oxalate \((C_2O_4)^{2-}\) which is a bidentate ligand, and ammonia \((NH_3)\) which is a monodentate ligand.

2. **Determine the Coordination Number**:
In an octahedral complex, the coordination number is 6. Each oxalate ligand occupies 2 coordination sites (since it is bidentate), and each ammonia occupies 1 coordination site. Therefore, the total coordination sites occupied is:
\[ 2 \times 2 + 2 \times 1 = 4 + 2 = 6 \]
This confirms that the arrangement is correct.

3. **Identify Possible Geometrical Isomers**:
In octahedral complexes, geometrical isomers can be classified as cis and trans isomers.

- **Cis Isomers**: In this case, the two bidentate oxalate ligands can be adjacent to each other. This arrangement can occur in two different configurations due to the spatial arrangement of the ligands.
- **Trans Isomers**: The two bidentate oxalate ligands can also be positioned opposite to each other, leading to one unique trans configuration.

4. **Count the Isomers**:
- **Cis Isomers**: There are 2 possible cis configurations (due to the two different arrangements of the oxalate ligands).
- **Trans Isomer**: There is 1 possible trans configuration.

Therefore, the total number of isomers is:
\[ 2 \text{ (cis)} + 1 \text{ (trans)} = 3 \text{ isomers} \]

5. **Conclusion**:
The total number of possible isomers for the complex \([Co(C_2O_4)_2(NH_3)_2]^-\) is **3**.