MHTCET 10 May 2024 Shift 2 Paper

Concept:A ligand is classified by the number of donor atoms it uses to bond to the central metal ion.A monodentate ligand attaches through only one donor atom.Explanation:In tetracyanonickelate(II) ion, $\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$, each cyanide ion $\mathrm{CN}^-$ is a monodentate ligand because it binds through only one atom (carbon).Potassium trioxalatoaluminate(III) contains oxalate, $\mathrm{C}_2\mathrm{O}_4^{2-}$, which is a bidentate ligand as it coordinates through two oxygen atoms.Trioxalatocobaltate(III) ion, $\left[\mathrm{Co}\left(\mathrm{C}_2\mathrm{O}_4\right)_3\right]^{3-}$, also has bidentate oxalate ligands.Bis(ethylenediamine)dithiocyanatoplatinum(IV) has ethylenediamine (en), a bidentate ligand, and thiocyanato, $\mathrm{SCN}^-$, which is an ambidentate ligand.Thus, only tetracyanonickelate(II) ion contains a purely monodentate ligand.Answer:Option A: Tetracyanonickelate(II) ion.