Oxidation of Ru(III)‐Bound Thiocyanate with Peroxomonosulfate: Kinetic and Mechanistic Studies |
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Authors: | Papiya Sarkar Debabrata Chatterjee |
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Affiliation: | Chemistry & Biomimetics Group, CSIR‐Central Mechanical Engineering Research Institute, Durgapur, India |
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Abstract: | The reaction of [RuIII(edta)(SCN)]2? (edta4? = ethylenediaminetetraacetate; SCN? = thiocyanate ion) with the peroxomonosulfate ion (HSO5?) has been studied by using stopped‐flow and rapid scan spectrophotometry as a function of [RuIII(edta)], [HSO5?], and temperature (15–30ºC) at constant pH 6.2 (phosphate buffer). Spectral analyses and kinetic data are suggestive of a pathway in which HSO5? effects the oxidation of the coordinated SCN? by its direct attack at the S‐atom (of SCN?) coordinated to the RuIII(edta). The high negative value of entropy of activation (ΔS≠ = ?90 ± 6 J mol?1 deg?1) is consistent with the values reported for the oxygen atom transfer process involving heterolytic cleavage of the O‐O bond in HSO5?. Formation of SO42?, SO32?, and OCN? was identified as oxidation products in ESI‐MS experiments. A detailed mechanism in agreement with the spectral and kinetic data is presented. |
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