Which from following complexes contains anionic ligand?
Which from following complexes contains anionic ligand?
Tetraamminecopper (II) ion
Pentaammineaquacobalt (III) iodide
Tetracyanonickelate (II) ion
Pentacarbonyliron(o)
Solution
To identify the complex containing an anionic ligand, examine the charge characteristics of each ligand in the coordination sphere.
In the tetraamminecopper(II) ion $[\mathrm{Cu}(\mathrm{NH}_3)4]^{2+}$, the ammine ligand $\mathrm{NH}_{3}$ is neutral.
The pentaammineaquacobalt(III) iodide complex $[\mathrm{Co}(\mathrm{NH}_3)5(\mathrm{H}_2 \mathrm{O})]^{3+}$ contains neutral ammine and aqua ligands $\mathrm{NH}_{3}$ and $\mathrm{H}_2 \mathrm{O}$.
In tetracyanonickelate(II) ion $[\mathrm{Ni(CN)}_4]^{2-}$, the cyano ligand $\mathrm{CN}^{-}$ carries a $-1$ charge, confirming its anionic character.
Pentacarbonyliron(0) $[\mathrm{Fe(CO)}_{5}]$ features the neutral carbonyl ligand $\mathrm{CO}$.
The tetracyanonickelate(II) ion is the only complex with an anionic ligand.