MCQ
The most stable ion is
  • A
    ${[Fe{(OH)_3}]^{3 - }}$
  • B
    ${[Fe{(Cl)_6}]^{3 - }}$
  • C
    ${[Fe{({H_2}O)_6}]^{3 + }}$
  • ${[Fe{(CN)_6}]^{3 - }}$

Answer

Correct option: D.
${[Fe{(CN)_6}]^{3 - }}$
d
The cyano and hydroxo complexes are far more stable than those formed by halide ion. This is due to the fact that $C N^{-}$ and $O H^{-}$ are strong lewis bases (nucleophiles). Further $\left[F e(O H)_{5}\right]^{-3}$ is not formed. hence most stable ion is $\left[F e(C N)_{6}\right]^{-3}$

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