The octahedral complex/complex ion which shown both facial and meridional isomers is

Options

A. triglycinato cobalt (II)
B. tris (ethylene diamine) cobalt (III)
C. dichloro diglycinato cobalt (III)
D. trioxalate cobaltate (III)

Answer

To determine the octahedral complex that shows both facial and meridional isomers, we need to analyze the types of ligands involved and their arrangements around the central metal atom.

### Step-by-Step Solution:

1. **Understanding Isomers**:
- Facial (fac) isomers occur when three identical ligands occupy one face of the octahedron, while meridional (mer) isomers occur when the identical ligands are arranged in a plane that divides the octahedron into two equal halves.

2. **Identifying Ligand Types**:
- We need a complex where the ligands can be classified into two types: monodentate and bidentate. Monodentate ligands attach through one donor atom, while bidentate ligands attach through two donor atoms.

3. **Analyzing the Given Complexes**:
- We will analyze the complexes mentioned in the video transcript:
- **Triglycinate cobalt(II)**: Glycinate is a bidentate ligand (can bind through N and O), thus it can form both fac and mer isomers.
- **Tris(ethylenediamine) cobalt(III)**: Ethylenediamine is a bidentate ligand, but since all ligands are the same, it cannot form fac and mer isomers.
- **Dichloroglycinate cobalt(III)**: This complex has both bidentate and monodentate ligands, but the arrangement does not allow for fac and mer isomers.
- **Tri-oxalate cobalt(III)**: Oxalate is also a bidentate ligand, and similar to ethylenediamine, it cannot form fac and mer isomers.

4. **Conclusion**:
- The only complex that shows both facial and meridional isomers is **Triglycinate cobalt(II)**, as it has the required arrangement of ligands to allow for both types of isomerism.

### Final Answer:
The octahedral complex that shows both facial and meridional isomers is **Triglycinate cobalt(II)**.