Chemistry - Coordination Chemistry Question with Solution | TestHub

${\left[\mathrm{Co}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}; {\mathrm{t}}_{2\mathrm{g}}^6{\mathrm{e}}_{\mathrm{g}}^0;$ CFSE $=\left[-0.4\times 6+0.6\times 1\right]{\mathrm{\Delta }}_{\mathrm{o}}+2\mathrm{P}=-1.8{\mathrm{\Delta }}_{\mathrm{o}}+2\mathrm{P}$

${\left[\mathrm{Co}{\left(\mathrm{CN}\right)}_6\right]}^{3-}; {\mathrm{t}}_{2\mathrm{g}}^6{\mathrm{e}}_{\mathrm{g}}^0;$ CFSE $=\left[-0.4\times 6+0.6\times 0\right]{\mathrm{\Delta }}_{\mathrm{o}}+2\mathrm{P}=-2.4{\mathrm{\Delta }}_{\mathrm{o}}+2\mathrm{P}$

Since ${\mathrm{CN}}^{-1}$ is a strong field ligand, ${\mathrm{\Delta }}_{\mathrm{o}}$ of this complex will be higher than that of ${\left[\mathrm{Co}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{3+}$