Select the correct `IUPAC` name of `[C_(4)H_(4)Fe(CO)_(3)]` complex .

Options

A. `eta^(4)`-cyclebutadiene tricarbonyliron(0)
B. Tricarbonyl `(eta^(4)`-cyclobutadienyl)iron(0)
C. Tricarbonyl `(eta^(4)`-cyclobutadienyl)iron(1)
D. Tricarbonyl `(eta^(4)`-cyclobutadienyl)iron(0)

Answer

To determine the correct IUPAC name of the complex \([C_{4}H_{4}Fe(CO)_{3}]\), we will follow these steps:

### Step 1: Identify the Ligands
The complex contains two types of ligands:
1. Carbon monoxide (CO) - a neutral ligand.
2. Cyclobutadiene (\(C_4H_4\)) - a neutral ligand that acts as a \(\eta^4\) (pi-acceptor) ligand.

### Step 2: Determine the Oxidation State of the Metal
Since both ligands (CO and cyclobutadiene) are neutral, the oxidation state of iron (Fe) in this complex is 0.

### Step 3: Naming the Ligands
According to IUPAC naming conventions:
- For the three CO ligands, we use the prefix "tri" to indicate there are three of them. Thus, we name it "tricarbonyl".
- For the cyclobutadiene ligand, since it is a \(\eta^4\) ligand, we denote it as "eta to the power 4 cyclobutadiene".

### Step 4: Combine the Names
Now we combine the names of the ligands with the name of the metal and its oxidation state:
- The name of the metal (iron) is followed by its oxidation state in Roman numerals (0).
- Therefore, the complete name becomes "tricarbonyl eta to the power 4 cyclobutadiene iron(0)".

### Final Answer
The correct IUPAC name of the complex \([C_{4}H_{4}Fe(CO)_{3}]\) is:
**tricarbonyl eta to the power 4 cyclobutadiene iron(0)**.

---