$CN ^{-}$is strong field ligand
$Fe ^{+3}\; 3 d ^{5}\;(t_{2 g}^{5} e_{g}^{0})$
$\text { CFSE }=5\left(-0.4 \Delta_{0}\right)=-2.0 \Delta_{0}$
$($At. No. $Mo = 42, Pt = 78)$