Question

According to IUPAC nomenclature, sodium nitroprusside is named as
(A) Sodium pentacyanonitrosyl ferrate (III)
(B) Sodium nitroferricyanide
(C) Sodium nitro ferrocyanide
(D) Sodium pentacyanonitrosyl ferrate (II)

Answer 1

In order to give the IUPAC name to the sodium nitroprusside, we must be aware of the rules set by the International Union for Pure and applied chemistry to name the coordination compounds.

Complete step by step solution:
We have to understand about various rules for naming the coordination complexes such as
- when we are naming the whole compound, we have to name the cation first and then the anion.
- when we are naming the complex ion, we have to name the ligand first, then comes the central metal ion.
- The ligands which are anionic will end with the letter ‘o’. For example, $- C{l^ - }$- Chloro.
- When there are more ligands, then we have to use Greek prefix such as mono, di, tri, tetra, Penta.
- When we are using the Roman numerals or zero in parenthesis, it will indicate the oxidation number of the central metal ion.
- When the complex ion is negative, then the name of the metal will end with ‘ate’. For example, cuprate, cobaltate.
- Ligands present in the complex are named in the alphabetical order.
- we have to write the name of the complex in a single word.
Now let us come to sodium nitroprusside. The chemical formula for sodium nitroprusside is $N{a_2}[Fe{(CN)_5}NO]$. On seeing the chemical formula, the complex is named as Sodium pentanitrosylferrate (III).

Therefore, the correct answer is an option (A).

Note: The oxidation number of the central metal ion can be calculated by taking the oxidation number of the central metal ion as x and then the substituting the actual oxidation number of the ligands. Then finally calculating we will obtain the oxidation number of the central metal ion.