Question

Reaction of $\left[Co\right(H_{2}O{)}_6{]}^{2+}$ with excess ammonia and in the presence of oxygen results into a diamagnetic product. Number of electrons present in $t_{2g}$-orbitals of the product is _______.

• A. 6.0
• B. 6
• C. 6.00

Answer 1

Answer: (A), (B), (C)

$\left[Co\right(H_{2}O{)}_6{]}^{2+}\underset{O_2}{\overset{N{H}_3}{\to }}\left[Co\right(N{H}_3{)}_6{]}^{3+}+e^{-}$
$C{o}^{3+}⟶3d^6$
$N{H}_3$ is a strong field ligand.
Hence, CFSE will be more than the pairing energy which will lead to the pairing of all the $e^{-}$ in the lower energy $t_{2g}$.
$3d^6⟶t_{2g}^6{e}_g^0$
So, the number of electrons present in $t_{2g}$ is 6.