`[Co_(2)(CO)_(8)]` displays :

Options

A. one Co-Co bond , two terminal CO and four bridging CO
B. one Co-Co bond , six teminal CO and two bridging CO
C. no Co-Co bond , four teminal CO and four bridging CO
D. on Co-Co bond , six teminal CO and four bridging CO

Answer

To analyze the coordination compound `[Co₂(CO)₈]`, we will follow these steps to determine its structure and characteristics:

### Step 1: Identify the Components
The given compound is `[Co₂(CO)₈]`. Here, we have:
- 2 cobalt (Co) metal centers.
- 8 carbonyl (CO) ligands.

### Step 2: Determine the Type of Ligands
Carbonyl (CO) is a neutral ligand and a strong field ligand. It can act as both a terminal ligand and a bridging ligand.

### Step 3: Analyze the Coordination Environment
In `[Co₂(CO)₈]`, we can have:
- 6 terminal carbonyl ligands.
- 2 bridging carbonyl ligands.

### Step 4: Draw the Structure
The structure can be visualized as:
- Two cobalt atoms bonded to each other (Co-Co bond).
- 6 carbonyl ligands attached to each cobalt atom as terminal ligands.
- 2 carbonyl ligands acting as bridging ligands between the two cobalt atoms.

### Step 5: Confirm the Coordination Number
Each cobalt atom is coordinated by 4 carbonyl ligands (2 terminal and 1 bridging from each side), leading to a total coordination number of 4 for each cobalt.

### Step 6: Identify the Correct Option
Based on the above analysis, we can evaluate the options provided in the question:
1. **Option 1**: Incorrect - It states there are 2 terminal carbonyls.
2. **Option 2**: Correct - It accurately describes 1 Co-Co bond, 6 terminal carbonyls, and 2 bridging carbonyls.
3. **Option 3**: Incorrect - It states there is no Co-Co bond.
4. **Option 4**: Incorrect - Similar to option 3, it states there is no Co-Co bond.

### Conclusion
The correct option is **Option 2**.

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