Some reactions of pentacyanosulphitoferrate(II) with oxidising agents

Abstract

Oxidation of the species [Fe^II(CN)₅(SO₃)]^5– by one equivalent of the oxidising agents [Ir^IVCl₆]^2– and [Fe^III(CN)₆]^3– leads rapidly to the formation of the complex [Fe^III(CN)₅(SO₃)]^4– which reacts with an excess of [Ir^IVCl₆]^2– to form [Fe^III(CN)₅(OH₂)]^2– and [SO₄]^2–. Further oxidation of [Fe^III(CN)₅(SO₃)]^4– by Br₂ gives a red complex (λ_max. 490 nm). The observed first-order rate constants for the reactions of [Fe^III(CN)₅(SO₃)]^4– with the different oxidants are the same, and are independent of the concentration of the oxidant.