Consider the following test for a group-IV cation. $\begin{aligned} & \mathrm{M}^{2+} +…
Consider the following test for a group-IV cation.
$\begin{aligned} & \mathrm{M}^{2+} + \mathrm{H}_2\mathrm{S} \rightarrow \mathrm{A} \text{ (Black precipitate)} + \text{ by product} \\ & \mathrm{A} + \text{ aqua regia } \rightarrow \mathrm{B} + \mathrm{NOCl} + \mathrm{S} + \mathrm{H}_2\mathrm{O} \\ & \mathrm{B} + \mathrm{KNO}_2 + \mathrm{CH}_3\mathrm{COOH} \rightarrow \mathrm{C} + \text{ by product} \end{aligned}$
The spin-only magnetic moment value of the metal complex $\mathrm{C}$ is ______ BM (Nearest integer)
Solution
If \(M^{+2}=C o^{+2}\)
then
\(\begin{aligned}
& \mathrm{Co}^{+2}+\mathrm{H}_2 \mathrm{~S} \rightarrow \underset{\substack{\text { Black } \\
\text { [A] }}}{\mathrm{CoS}}+\text { byproduct } \\
& \mathrm{CoS}+\text { aqua regia } \rightarrow \underset{\text{[B]}}{\mathrm{CoCl}_2}+\mathrm{NOCl}+\mathrm{S}+\mathrm{H}_2 \mathrm{O}
\end{aligned}\)
\(\mathrm{CoCl}_2+\mathrm{KNO}_2 \xrightarrow{\mathrm{CH}_3 \mathrm{COOH}} k_3\left[\mathrm{CO}\left(\mathrm{NO}_2\right)_6\right]+\text { byproduct }\)
\([C]=C o^{+3} \rightarrow 3 d^6 \Rightarrow N O_2\) is SFL so Co +3 has zero unpaired \(e^{-}\)
\(\Rightarrow n=0 \Rightarrow u=\sqrt{n(n+2)}=0 B . M\)