Preparation and characterization of manganese(iv) in aqueous acetic acid

Abstract

Mn(IV) acetate was generated in acetic acid solutions and characterized by UV-vis spectroscopy, magnetic susceptibility, and chemical reactivity. All of the data are consistent with a mononuclear manganese(IV) species. Oxidation of several substrates was studied in glacial acetic acid (HOAc) and in 95 : 5 HOAc–H₂O. The reaction with excess Mn(OAc)₂ produces Mn(OAc)₃ quantitatively with mixed second-order kinetics, k (25.0 °C) = 110 ± 4 M⁻¹ s⁻¹ in glacial acetic acid, and 149 ± 3 M⁻¹ s⁻¹ in 95% AcOH, ΔH^‡ = 55.0 ± 1.2 kJ mol⁻¹, ΔS^‡ = −18.9 ± 4.1 J mol⁻¹ K⁻¹. Sodium bromide is oxidized to bromine with mixed second order kinetics in glacial acetic acid, k = 220 ± 3 M⁻¹ s⁻¹ at 25 °C. In 95% HOAc, saturation kinetics were observed.