Question

The IUPAC name of $[\mathrm{Cr}{\left(\mathrm{CN}\right)}_6{]}^{3-}$ is

Answer 1

IUPAC Nomenclature of Coordination Compounds
• The cation's name comes first, followed by the anion's name.
• The ligand or ligands' name comes before the name of the central metal atom.
• If the ligand is negative, the name usually ends in 'o', and if the ligand is neutral, it usually ends in 'unmodified.'
• The number of ligands is indicated by a Greek prefix, such as mono, di, tri, tetra, penta, hexa, and so on.
• The oxidation number of the central metal atom is indicated by a Roman numeral or a zero in parenthesis.
• The name of the metal ends in 'ate' if the complex ion is negative, such as ferrate, cuprate, nickelate, cobaltate, and so on.
• If the species contains more than one ligand, the ligands are called in alphabetical order, regardless of their number.

Oxidation state of $[\mathrm{Cr}{\left(\mathrm{CN}\right)}_6{]}^{3-}$

The oxidation state of chromium is as follows:-

$$\begin{gathered} x-6=-3 \\ x=+3 \end{gathered}$$

So, the oxidation state of chromium is $+3$.

IUPAC name of $[\mathrm{Cr}{\left(\mathrm{CN}\right)}_6{]}^{3-}$

• Six cyanide ligands is present, so the name for the ligand is Hexacyano.
• The given complex ion is an anion, the name of the chromium ends with the suffix – ate which is chromate.
• So, the IUPAC name of $[\mathrm{Cr}{\left(\mathrm{CN}\right)}_6{]}^{3-}$is Hexacyano chromate(III).