Which one of the following complexes is violet in colour ?

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> JEE Main 2021

1. $F{e}_4\left[Fe\right(CN{)}_6{]}_3.H_{2}O$
2. $\left[Fe\right(SCN{)}_6{]}^{4-}$
3. $\left[Fe\right(CN{)}_6{]}^{4-}$
4. $\left[Fe\right(CN{)}_{5}NOS{]}^{4-}$

The correct option is D $\left[Fe\right(CN{)}_{5}NOS{]}^{4-}$
$\left[Fe\right(CN{)}_6{]}^{4-}$ - Plate yellow
$\left[Fe\right(CN{)}_6{]}^{3-}$ - Yellow
$Fe(SCN{)}_3$ - Red colouration
$\left[Fe\right(CN{)}_5\left(NOS\right){]}^{4-}$ - Violet colour

$N{a}_{2}S+\underset{\text{sodium nitroprusside}}{N{a}_2\left[Fe\right(CN{)}_{5}NO]}\to \underset{\text{sodium thionitroprusside (violet)}}{N{a}_4\left[Fe\right(CN{)}_{5}NOS]}$
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