JEE Chemistry 2023 Question with Solution

Given: The coordination compound is $K_3[Co(C_2O_4)_3]$.

Find: The correct IUPAC name of this compound.

The complex ion is $[Co(C_2O_4)_3]^{3-}$ and the ligand $C_2O_4^{2-}$ is oxalato. Since there are three such ligands, the multiplicative prefix is tris(oxalato).

Because the complex species is an anion, the metal name becomes cobaltate. The oxidation state of cobalt is $+3$, so it is written as (III).

Therefore, the IUPAC name is Potassium tris(oxalato)cobaltate(III). The correct option is C.

Given: $K_3[Co(C_2O_4)_3]$

Find: Its IUPAC name.

Each potassium ion has charge $+1$, so the complex part must have charge $-3$.

Also, each oxalato ligand has charge $-2$. Let the oxidation state of cobalt be $x$.

So,

Thus the anionic complex is named with the metal as cobaltate(III). Since three oxalato ligands are present, the ligand part is tris(oxalato).

Hence the full name is Potassium tris(oxalato)cobaltate(III).