Which of the following complex compounds will exhibit highest paramagnetic behaviour? (At. no. :…
- $\left[\mathrm{Ti}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
- $\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
- $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
- $\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_6\right]^{2+}$
Solution
(B) Electronic configuration of $\mathrm{Cr}^{3+}$ in $\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
(C) Electronic configuration of $\mathrm{Co}^{3+}$ in $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ :
In the presence of strong field ligand $\mathrm{NH}_3$, pairing of electrons takes place and thus, octahedral complex, $\quad\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ is diamagnetic.
$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
$\left[\begin{array}{l}
\text { inner orbital or } \\
\text { low spin complex }
\end{array}\right]\left(6 \mathrm{NH}_3 \text { molecules }\right)$
(D) Electronic configuration of $\mathrm{Zn}^{2+}$ in $\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_6\right]^{2+}$ :
$\therefore\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_6\right]^{2+}$ is an outer orbital complex and is diamagnetic.Asked in: NEET 2011 (Mains)