Ferrocene is described by the formula

Options

A. `[Fe(CN)_6 ]^(3-)`
B. `[Fe(CN)_6 ]^(4-)`
C. `[Fe (CO)_5 ]`
D. `[Fe(C_5 H_5)_2 ]`

Explanation

### Step-by-Step Solution:

1. **Understanding Ferrocene**:
- Ferrocene is classified as an organometallic compound. Organometallic compounds are those in which a carbon atom is directly bonded to a metal atom.

2. **Identifying the Formula**:
- The chemical formula of ferrocene is given as Fe(C5H5)2. This indicates that there are two cyclopentadienyl (C5H5) ligands attached to a single iron (Fe) atom.

3. **Analyzing the Components**:
- Each cyclopentadienyl ligand (C5H5) consists of five carbon atoms and five hydrogen atoms. Therefore, with two ligands, the total number of carbon and hydrogen atoms in ferrocene is:
- Carbon: 5 (from one ligand) × 2 (ligands) = 10
- Hydrogen: 5 (from one ligand) × 2 (ligands) = 10
- Thus, the complete formula can be summarized as FeC10H10.

4. **IUPAC Naming**:
- The IUPAC name for ferrocene is bis(cyclopentadienyl)iron. The prefix "bis" indicates that there are two cyclopentadienyl ligands attached to the iron atom.

5. **Understanding the Structure**:
- Ferrocene has a unique "sandwich" structure where the iron atom is sandwiched between two cyclopentadienyl anions. Each cyclopentadienyl anion has a negative charge, and the iron is typically in the +2 oxidation state.

6. **Conclusion**:
- Therefore, the formula of ferrocene is Fe(C5H5)2, and its IUPAC name is bis(cyclopentadienyl)iron.