Electron-transfer oxidation of organic compounds with hexachloroantimonate [SbCl6]– ion
Abstract
Hexachloroantimonate [SbCl6]– salts of stable organic cations are shown to be active oxidising agents for aromatic amines, ferrocene, phenoxide ions, and iodide ion. Tetra-alkylammonium hexachloroantimonates oxidise Leuco Crystal Violet to Crystal Violet by apparent hydride-abstraction. Kinetic studies show that the reactions have very low activation-energies and an approximate value for the primary kinetic isotope effect kCH/kCD∼ 2·5. It is possible therefore that [SbCl6]– functions primarily as a one-electron oxidant. Complex chlorides of SbIII are produced in the oxidations and new crystalline salts of [SbCl4]–, [Sb2Cl9]3–, and the very unstable [SbCl6]3– have been characterised. Photolysis of [Me2Ph(PhCH2)N]+[SbCl6]– in tetrahydrofuran gives an apparent chain-reaction in which hydrogen chloride and [Me2Ph(PhCH2)N]+3[Sb2Cl9]3– are formed in very high yield.