Geometrical shapes of the complexes formed by the reaction of $\mathrm{Ni}^{2+}$ with $\mathrm{Cl}^{-}, \mathrm{CN}^{-}$and $\mathrm{H}_{2} \mathrm{O}$, respectively, are

(B) tetrahedral, square planar and octahedral

(A) octahedral, tetrahedral and square planar

(C) square planar, tetrahedral and octahedral

(D) octahedral, square planar and octahedral

JEE Advanced · 2011 · 10 Apr 2011 · Paper 1 · Coordination Compounds

Geometrical shapes of the complexes formed by the reaction of

Ni^{2 +}

with

Cl^{-}, CN^{-}

and

H_{2} O

, respectively, are

Answer: (B)

Ni^{2 +}

forms different geometries with different ligands:

With $Cl^{-}$ (weak field ligand): $[NiCl_{4}]^{2 -}$ is tetrahedral (high spin, $s p^{3}$ hybridization)
With $CN^{-}$ (strong field ligand): $[Ni (CN)_{4}]^{2 -}$ is square planar (low spin, $d s p^{2}$ hybridization)
With $H_{2} O$ (weak field ligand): $[Ni (H_{2} O)_{6}]^{2 +}$ is octahedral (high spin, $s p^{3} d^{2}$ hybridization)

The order is tetrahedral, square planar, and octahedral.

JEE Advanced · 2011 · 10 Apr 2011 · Paper 1 · Single correct option