Chemistry - Coordination Chemistry Question with Solution | TestHub

${\mathrm{Fe}}^{2+}$ electronic configuration is $[\mathrm{Ar}]3{\mathrm{d}}^6$. Since CN is strong field ligand d electrons are paired . In $\mathrm{Ni}(\mathrm{CO}{)}_4\mathrm{O}.\mathrm{S}$. of $\mathrm{Ni}$ is zero electronic configuration is $[\mathrm{Ar}\}3{\mathrm{d}}^{8}4{\mathrm{s}}^2.\mathrm{In}$ presence of $\mathrm{CO}$ it is $[\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^0,$ electrons are paired. Electronic configuration of ${\mathrm{Ni}}^{2+}$ $[\mathrm{Ar}]3{\mathrm{d}}^{8}4{\mathrm{s}}^0,$ due to ${\mathrm{CN}}^{-}$ ligand all electrons are paired. ${\mathrm{Co}}^{3+}$ is $[\mathrm{Ar}]3{\mathrm{d}}^6$ since $\mathrm{F}$ is weak ligand hence paramagnetic.