Question

In which of the following complex ion, the central metal ion is in a state of $s{p}^3{d}^2$ hybridisation?

• A. $[Co{F}_6{]}^{3-}$
• B. $\left[Co\right(N{H}_3{)}_6{]}^{3+}$
• C. $\left[Fe\right(CN{)}_6{]}^{3-}$
• D. $\left[Cr\right(N{H}_3{)}_6{]}^{3+}$

Answer 1

The correct option is A $[Co{F}_6{]}^{3-}$

$F^{-}$ is a weak ligand. It cannot pair up d-electrons and forms outer orbital octahedral complex.
$N{H}_3$ and $C{N}^{-}$ are strong ligands. So, they pair up d-electrons and form their inner orbital complex.