Mechanistic studies on oxidation of hydrogen peroxide and hydrazine by a metal-bound superoxide |
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Authors: | Sekhar Gain Rupendranath Banerjee |
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Institution: | Department of Chemistry, Jadavpur University, Kolkata 700032, India |
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Abstract: | In aqueous acetate buffer, hydrogen peroxide and hydrazine reduce the bridging superoxide in (en)(dien)CoIII(O2)CoIII(en)(dien)](ClO4)5 (1) to the corresponding hydroperoxo complex (en)(dien)CoIII(μ-O2H)CoIII(en)(dien)]5+ (2). In the presence of excess H2O2] and N2H5+] over 1], both the reactions obeyed first-order kinetics and exhibited inverse proton dependence. Protonation of 1 at equilibrium generates (en)(dien)CoIII(μ-O2H)CoIII(en)(dien)]6+ (1H), the conjugate acid from 1, which appears to be a kinetic dead-end and that accounts for the observed inverse proton dependence on rate. Reaction rates significantly decrease with increasing proportion of D2O replacing H2O in the solvent and an H-atom transfer (HAT) from the reducing species to the bridging superoxide in 1 seems reasonable at the rate step. |
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Keywords: | Kinetics Mechanisms Hydrogen peroxide Hydrazine Superoxo Reduction |
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