Question

According to the IUPAC nomenclature, sodium nitroprusside is named as,
A.Sodium nitro-ferrocyanide
B.Sodium pentacyanonitrosylferrate (ll)
C.Sodium nitroferricyanide
D.Sodium pentacyanonitrosylferrate (lll)

Answer 1

Hint: Sodium nitroprusside is a coordination compound. IUPAC has proposed certain rules for the nomenclature of coordination compounds.

Complete step by step answer:The formula of sodium nitroprusside is $N{a_2}\left[ {Fe{{(CN)}_5}NO} \right]$.
The rules for nomenclature of coordination compounds are,
Cation is named first.
In the naming of coordination entities, ligands are named first and then the metal ion. The oxidation number of metal ions is given in Roman numbers in parentheses placed just after the name of metal ions.
Ligands are named in the alphabetical order.
Name of anionic ligands ends with –o. Names of cationic and neutral ligands are as written as such.
Prefixes mono, di, tri etc is used to indicate the number of ligands. When names of ligands contain numerical prefixes, then the terms bis, tris, tetrakis etc are used.
If the complex ion is cation, the name of the metal is written the same as the element. If the complex ion is anion, the name of the metal is written with a suffix -ate.
Now let us name the given compound.
In $N{a_2}\left[ {Fe{{(CN)}_5}NO} \right]$, complex ion is anion. So the name starts with cation, sodium. The ligands are cyanide ($C{N^ - }$) and nitrosyl (NO). Cyanide is anion. Hence it will be named as cyano. There are five cyanide ligands. Hence prefix penta will be used. Nitrosyl is a neutral ligand. The metal inside the coordination entity is iron. Hence it will be written as ferrate. Its oxidation state is three. Hence the name of the compound will be Sodium pentacyanonitrosylferrate(III).
Therefore, the correct option is D.

Note:
To name coordination compounds, first we should know the names of ligands with their oxidation states. Calculation of oxidation state of metal is very important in naming.The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation of an atom in a chemical compound.