Showing papers by "Miguel Ferrer published in 1980"
TL;DR: In this paper, it was concluded that there is little or no Fe2+(10−3 M) reduction of µ-hydroxo-µ-peroxo-dicobalt(III) complexes and that the reaction observed, [H+]= 0.01 and 0.10 M, is accounted for by H+-induced hydroxo bridge cleavage leading to mononuclear products.
Abstract: It is concluded that there is little or no Fe2+(10–3 M) reduction of the µ-hydroxo-µ-peroxo-dicobalt(III) complexes [(en)2Co(OH)(O2)Co(en)2]3+ and [(trien)Co(OH)(O2) Co(trien)]3+ and that the reaction observed, [H+]= 0.01 and 0.10 M, is accounted for by H+-induced hydroxo-bridge cleavage leading to mononuclear products (en = ethylenediamine, trien = triethylenetetra-amine). Contrary to a previous report µ-peroxo-complexes remain less active than H2O2 with Fe2+ as reductant.
5 citations
TL;DR: In this article, the decomposition of the µ-peroxo-bis[penta-amminecobalt(III)] complex was studied using the stopped-flow technique at [H+]= 0.005−0.100M, I= 0.10M(LiClO4), and the acid dissociation constant K of the protonated (red) complex (25 °C) was 0.
Abstract: The kinetics of the decomposition of the µ-peroxo-bis[penta-amminecobalt(III)] complex, [(NH3)5Co·O2·Co(NH3)5]4+ [graphics omitted] 2Co2++ O2+ 10 NH4+, generated by fast one-electron reduction of the µ-superoxo-complex, [(NH3)5·Co·O2·Co(NH3)5]5+, have been studied using the stopped-flow technique at [H+]= 0.005–0.100M, I= 0.10M(LiClO4). The [H+] dependence of first-order rate constants, kobs=kK/([H+]+K), is consistent with the formation of a protonated non-reactive form. At 25 °C the rate constant for decomposition of the unprotonated (brown) form is k= 84 s–1, and ΔH‡= 17.5 ± 1.0 kcal mol–1, ΔS‡= 8.7 ± 3.7 cal K–1 mol–1, in excellent agreement with previous data for solutions [NH3]= 4.3–15.0M,I= 2.0M(NH4NO3). The acid dissociation constant K of the protonated (red) complex (25 °C) is 0.084M, with ΔH= 6.0 ± 2.5 kcal mol–1, ΔS= 15.2 ± 9.0 cal K–1 mol–1. Chloride 0.6M the effect of [H+] and [Cl–] on the rate of decomposition was studied by conventional spectrophotometry, I= 2.3M(Cl–/ClO4). Solid samples of the brown and red complexes interconvert rapidly in solution to give identical spectra. The protonated red complex does not react with iodide during the ca. 30 min period required for decomposition. Implications regarding the structure of the protonated complex are considered.
4 citations