The correct option(s) regarding the complex $\left[\mathrm{Co}(e n)\left(\mathrm{NH}_{3}\right)_{3}\

Question

The correct option(s) regarding the complex $\left[\mathrm{Co}(e n)\left(\mathrm{NH}_{3}ight)_{3}\left(\mathrm{H}_{2} \mathrm{O}ight)ight]^{3+}\left(e n=\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}ight)$ is (are)\

Professor PC Thomas Classes · Answer

$(\mathrm{a}, \mathrm{b}, \mathrm{d}):$\(a)$\left[\mathrm{Co}(\text { en })\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}$\(b)$\left[\mathrm{Co}(\mathrm{CN})_{2}\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{+}$\(c)$\mathrm{Co}^{3+}:[\mathrm{Ar}] 3 d^{6}$ in presence of en and $\mathrm{NH}_{3}$ it forms low spin complex.\ $\mathrm{Co}^{3+}$ in $\left[\mathrm{Co}(e n)\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}$ :\ Due to absence of unpaired electron, this complex is diamagentic in nature.\  \ (d)  $\left[\mathrm{Co}(e n)\left(\mathrm{NH}_{3}\right)_{4}\right]^{3+}$ has larger energy gap between $t_{2 g}$ and $e_{g}$ than $\left[\mathrm{Co}(\text { en })\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}$ as $\mathrm{NH}_{3}$ is stronger ligand than $\mathrm{H}_{2} \mathrm{O}$. So, $[\mathrm{Co}($ en $)$ $\left.\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}$ absorbs longer wavelength than $\left[\mathrm{Co}(e n)\left(\mathrm{NH}_{3}\right)_{4}\right]^{3+}$.\