JEE Main 2013 — Coordination Compounds Question with Solution

${\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}^{3-}$ has magnetic moment of a single unpaired electron whereas ${\left[{\mathrm{FeF}}_6\right]}^{3-}$ has a magnetic moment of five unpaired electrons. ${\left[{\mathrm{CoF}}_6\right]}^{3-}$ is paramagnetic with four unpaired electrons while ${\left[\mathrm{Co}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3\right]}^3$ is diamagnetic. This anomaly is explained by valence bond theory in terms of formation of inner and outer orbital coordination entities. ${\left[\mathrm{Co}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3\right]}^{3-}$ is an inner orbital complexes having $d^{2}s{p}^3$ hybridization.