The correct IUPAC name of the coordination compound `K_(3) [Fe(CN)_(5) NO]` is

Options

A. potassium pentacyanonitrosylferrate (II)
B. potassium pentacyanonitroferrate(III)
C. potassium nitritopentacyanoferrate(IV)
D. potassium nitritepentacyanoiron (II) .

Answer

To determine the correct IUPAC name of the coordination compound \( K_3[Fe(CN)_5NO] \), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Components**:
The compound consists of potassium ions \( K^+ \) and the coordination complex \( [Fe(CN)_5NO]^{3-} \).

2. **Determine the Charge of the Coordination Complex**:
Since there are three potassium ions, the overall charge contributed by potassium is \( +3 \). Therefore, the charge of the coordination complex must be \( -3 \) to balance the charges.

3. **Find the Oxidation State of Iron**:
In the complex \( [Fe(CN)_5NO]^{3-} \):
- Each cyanide ion \( (CN^-) \) contributes a charge of \( -1 \). With five cyanide ions, the total contribution is \( -5 \).
- The nitrosyl \( (NO) \) is neutral in this context (considered as \( 0 \)).
- Let the oxidation state of iron be \( x \). Therefore, we can set up the equation:
\[ x - 5 + 0 = -3 \]
Solving for \( x \):
\[ x - 5 = -3 \implies x = +2 \]
Thus, the oxidation state of iron is \( +2 \).

4. **Naming the Ligands**:
- The ligands are \( CN^- \) (cyano) and \( NO \) (nitrosyl).
- The prefix for five cyano ligands is "penta".

5. **Order of Naming**:
According to IUPAC nomenclature, ligands are named in alphabetical order, regardless of their prefixes.
- "Cyano" comes before "Nitrosyl" alphabetically.

6. **Construct the Name**:
The overall name starts with the cation followed by the anionic complex:
- Cation: Potassium (from \( K^+ \))
- Anionic complex: "pentacyanonitrosylferrate"
- Since the oxidation state of iron is +2, we denote it as "ferrate(II)" or "ferrate second".

7. **Final IUPAC Name**:
Combining all parts, the correct IUPAC name is:
\[ \text{Potassium pentacyanonitrosylferrate(II)} \]

### Final Answer:
**Potassium pentacyanonitrosylferrate(II)**