Question

If all the ligands in the co-ordination sphere of the above complex are replaced by $C{N}^{-}$ ion, then the magnetic moment of the complex ion will be

• A. $0.0BM$
• B. $5.9BM$
• C. $4.9BM$
• D. $1.73BM$

Answer 1

The correct option is A $0.0BM$

Loss of water on treatment with sulfuric acid indicates presence of water molecule in the ionization sphere. Yellow precipitate of AgI on treatment with silver nitrate indicates presence of the iodide ions in the ionization sphere.
Thus the complex is $\left[Co\right(en{)}_{2}IC{l}_2\left]\right(H_{2}O)I$. When the ligands are replaced with cyanide ligands, the complex formed is $\left[CoC{N}_4\right]$.
$C{o}^{3+}$ has $d^6$ electronic configuration.
It involves $d^{2}s{p}^3$ hybridization with 0 unpaired electrons and is diamagnetic. Its magnetic moment is 0.0 B.M.