For the octahedral complex of $F{e}^{3+}$ in $SC{N}^{-}$ and in $C{N}^{-}$ ligand environments, the difference between spin only magnetic moment (in BM) ________ (approximated to the nearest integer) 

 $F{e}^{+3}=3d^5$
 ${\left[Fe{\left(SCN\right)}_6\right]}^{3-}$
 $SC{N}^{-}-$ Weak field ligand 
                -    pairing does not takes place
$n=5$ 
$\mu \simeq 5.9BM$ 
${\left[Fe{\left(CN\right)}_6\right]}^{3-}$ 
$C{N}^{-}$ - Strong field ligand
           - Pairing takes place
$n=1$ 
$\mu \simeq 1.7$ 
$\Delta =5.9-1.7\simeq 4$