Question

Select the correct statement among the following.

• A. $Co(III)$ is stabilised in presence of weak field ligands, while $Co(II)$ is stabilised in presence of strong field ligand.
• B. Four coordinated complexes of $Pd(II)$ and $Pt(II)$ are paramagnetic and square planar.
• C. ${\left[Ni(CN{)}_4\right]}^{4-}$ ion and $\left[Ni(CO{)}_4\right]$ are tetrahedral and square planar respectively.
• D. $N{i}^{2+}$ ion does not form inner orbital octahedral complexes in presence of weak ligand fields.

Answer 1

Answer: (D)

This problem includes conceptual mixing of CFSE, CFT and magnetism in coordination compounds. This problem can be solved by usual understanding of each statement as explained below :
(I) Both $C{o}^{2+}$ and $C{o}^{3+}$ are stabilised in presence of strong of field ligands due to high CFSE values.
(II) Due to higher Zeft values on the valence shell $P{d}^{2+}$ and $P{t}^{2+}$ cations, they always form inner orbital complexes but are diamagnetic in nature and square planar.
(III) $\left[Ni(CO{)}_4\right];s{p}^3$, tetrahedral, $\mu =0BM$
${\left[Ni(CN{)}_4\right]}^{4-};ds{p}^2$, square planar, $\mu =0BM$
(IV) In $N{i}^{+2}$, pairing of electron do not occur in presence of weak field ligands, so they form an outer orbital complex.

Electronic distribution unaffected.