Question

The reaction of nitroprusside anion with sulphide ion gives purple colouration due to the formation of:

• A. the tetranionic complex of iron (II) coordinating to one ${NOS}^{-}$ ion
• B. the dianionic complex of iron (II) coordinating to one ${NCS}^{-}$ ion
• C. the trianionic complex of iron (III) coordinating to one ${NOS}^{-}$ ion
• D. the tetranionic complex of iron (III) coordinating to one ${NCS}^{-}$ ion

Answer 1

The correct option is A the tetranionic complex of iron (II) coordinating to one ${NOS}^{-}$ ion

${Na}_{2}S+\underset{sodiumnitropruside}{{Na}_2\left[Fe{\left(CN\right)}_{5}NO\right]}⟶\underset{purplecolour}{{Na}_4\left[Fe{\left(CN\right)}_{5}NOS\right]}$
${Na}_4\left[Fe{\left(CN\right)}_{5}NOS\right]\rightleftharpoons 4{Na}^{+}+{\left[Fe{\left(CN\right)}_{5}NOS\right]}^{4-}$
tetra anionic complex of iron (III) coordinating to one $NO{S}^{-}$ ions.