$[Fe(CN)_6]^{3-}$ has magnetic moment of a single unpaired electron whereas $[FeF_6]^{3-}$ has a magnetic moment of five unpaired electrons. $[CoF_6]^{3-}$ is paramagnetic with four unpaired electrons while $[Co(C_2O_4)_3]^3$ is diamagnetic. This anomaly is explained by valence bond theory in terms of formation of inner and outer orbital coordination entities. $[Co(C_2O_4)_3]^{3-}$ is an inner orbital complexes having $d^2sp^3$ hybridization.