What is the correct IUPAC name for Fe(NO2)2?
The Correct Answer and Explanation is:
The correct IUPAC name for Fe(NO2)2 is iron(II) nitrite.
Explanation:
- Identify the metal and its oxidation state:
- The compound contains iron (Fe) and nitrite ions (NO2⁻).
- Nitrite ion is a polyatomic ion with a charge of –1.
- Since there are two nitrite ions, the total negative charge is –2.
- To balance this, iron must have a +2 charge.
- Therefore, iron is in the +2 oxidation state.
- Name of the cation:
- The cation is iron.
- Because iron can have multiple oxidation states (commonly +2 and +3), the oxidation state is indicated by Roman numerals in parentheses immediately after the metal name.
- Here, iron is +2, so it is named iron(II).
- Name of the anion:
- The anion is the nitrite ion, NO2⁻.
- The suffix “-ite” denotes the nitrite ion (less oxygen compared to nitrate, NO3⁻).
- The name of the anion is nitrite.
- Combine the names:
- The cation name with oxidation state + anion name = iron(II) nitrite.
Additional Notes:
- This is an ionic compound composed of a metal cation and a polyatomic anion.
- When naming ionic compounds with transition metals, indicating the oxidation state of the metal is essential because they can have multiple oxidation states.
- The oxidation state is determined from the known charge of the anion(s).
- The compound Fe(NO2)2 should not be confused with iron nitrate, Fe(NO3)2 or Fe(NO3)3, where the anion is nitrate (NO3⁻).
- The correct IUPAC naming follows the rules set by the International Union of Pure and Applied Chemistry to ensure consistency and clarity in chemical nomenclature.
Summary:
- Fe = Iron, with oxidation state +2 → iron(II)
- NO2⁻ = Nitrite ion → nitrite
- Hence, Fe(NO2)2 is named iron(II) nitrite.
