2003 AIPMT Coordination CompoundsIUPAC nomenclature of coordination compounds Medium Question 2 of 2 in IUPAC nomenclature of coordination compounds

According to IUPAC nomenclature sodium nitroprusside is named as :

A Sodium nitroferricyanide
B Sodium nitroferrocyanide
C Sodium pentacyanonitrosyl ferrate (II)
D Sodium pentacyanonitrosyl ferrate (III)

The answer is C.

Solution

Sodium nitroprusside is $Na_2[Fe(CN)_5NO]$.
The complex anion has five cyanide ligands ($CN^-$) and one nitrosyl ligand. In nitroprusside the NO ligand is present as $NO^+$ (nitrosonium).
Oxidation state of Fe: $x + 5(-1) + (+1) = -2 \Rightarrow x = +2$
The complex is an anion, so the metal name ends in -ate (ferrate). Ligands are named in alphabetical order: cyano before nitrosyl.
So its name is sodium pentacyanonitrosylferrate(II).

Concept Naming sodium nitroprusside

IUPAC nomenclature of coordination compounds in past papers

2 questions from this chapter have appeared across 2 exam years.