Question

Aqueous $Fe\left(III\right)$ ion develops intense red colour with $SC{N}^{-}$while $Fe\left(II\right)$ does not. It is due to:

• A. $Fe\left(III\right)$ ion forms a charge transfer complex with $SC{N}^{-}$ ions
• B. $Fe\left(III\right)$ is reduced to $Fe\left(I\right)$ which is deep red in colour
• C. $SC{N}^{-}$ ion oxidizes to $C{N}^{-}$ ion that forms red complex with $Fe\left(III\right)$ ion
• D. $SC{N}^{-}$ ion does not form any complex with $Fe\left(II\right)$ ion

Answer 1

Answer: (A)

$Fe\left(III\right)$ ion forms a charge transfer complex with $SC{N}^{-}$ ions

Aqueous $Fe\left(III\right)$ ion develops intense red colour with $SC{N}^{-}$ while $Fe\left(II\right)$ does not. It is due to $Fe\left(III\right)$ ion forms a charge transfer complex with $SC{N}^{-}$ ions.