Aliphatic radicals as reducing agents of cobalt(III) and ruthenium(III) complexes: A pulse radiolytic study

The pH effect on the rate of the reduction reaction ĊH₂OH + [Co(NH₃)₆]³⁺ has been studied. The results indicate that this reaction does not proceed via the outer-sphere mechanism. The pH effect on the reactivity of R¹Ċ(OH)CO₂H [R¹ = H,CH₃, or HO₂CCH(OH)] towards [Co(NH₃)₆]³⁺ and [Ru(NH₃)₆]³⁺ has been studied. The results indicate that the radicals R¹Ċ(OH)CO₂^- are considerably more reactive than R¹Ċ(OH)CO₂H. The reasons for this effect are discussed. The rate of water loss from the radical derived from tartaric acid has been measured. The kinetics of reduction of [CoX(NH₃)₅]²⁺ and [RuX(NH₃)₅]³⁺,(X = halide) and [Co^III(en)₂XY] (en = ethylenediamine; X,Y = F, Cl, Br, NH₃, or H₂O) by the radicals ĊH₂OH, MeĊHOH. Me₂ĊOH, Me₂ĊHOEt, and O-ĊH-CH₂-O-CH₂-CH₂ have been examined mechanism. The results suggest that these reactions proceed via a bridged mechanism.