Question

Which of the following, which is diamagnetic in nature?

• A. ${\left[Co{F}_6\right]}^{3-}$
• B. ${\left[NiC{l}_4\right]}^{2-}$
• C. ${\left[CuC{l}_4\right]}^{2-}$
• D. ${\left[Ni{\left(CN\right)}_4\right]}^{2-}$

Answer 1

The correct option is D ${\left[Ni{\left(CN\right)}_4\right]}^{2-}$

${\left[NiC{l}_4\right]}^{-2},$ 2 unpaired electron.
$N{i}^{+2},d^8,s{p}^3$ hybridization & tetrahedral geometry.
High spin complex as chloride is weak ligand.
${\left[Co{F}_6\right]}^{3-}$, $C{o}^{+3},d^6$ high spin complex, 4 unpair electron.
${\left[CuC{l}_4\right]}^{2-}$, $C{u}^{+2},d^9$, one unpaired electron.
${\left[Ni{\left(CN\right)}_4\right]}^{2-}$, $N{i}^{+2},d^8$ configuration, low spin complex so zero unpaired electron & diamagnetic.