Question

Several octahedral complexes are possible from combinations of $C{o}^{3+},C{l}^{-}$ and $N{H}_3$. The correct statement(s) regarding the octahedral coordination entities having the formula .$\left[Co\right(N{H}_3{)}_{n}C{l}_{6-n}{]}^{(n-3)+}$ with $n\ge 3$, is/ are_____________.

• A. At most six octahedral complexes are possible
• B. One of the complexes is homoleptic
• C. All the complexes are paramagnetic
• D. Some of the complexes dissociate in water to give $C{o}^{3+}$ and $C{l}^{-}$ ions

Answer 1

Answer: (A), (B)

The correct options are
A At most six octahedral complexes are possible
B One of the complexes is homoleptic

$\left[Co\right(N{H}_3{)}_{n}C{l}_{6-n}{]}^{(n-3{)}^{+}}$ $n\ge 3$

For $n=3,n=4,n=5,n=6$

For $n=6\Rightarrow \left[Co\right(N{H}_3{)}_6{]}^{3+}=$ is homopletic due to all 6 same ligands.

For $n=5\Rightarrow \left[Co\right(N{H}_3{)}_6{]}^{2+}$

For $n=4\Rightarrow \left[Co\right(N{H}_3{)}_6{]}^{+}=$

For $n=3\Rightarrow \left[Co\right(N{H}_3{)}_6]$

Only $4$ octahedral complex are possible.

One of them is homoleptic.