Kinetics and mechanism of the oxidation of iodide by trans-dioxoruthenium (VI)

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)22_Publication in policy or professional journal

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Original languageEnglish
Pages (from-to)3091-3093
Journal / PublicationJournal of the Chemical Society, Dalton Transactions
Issue number21
Publication statusPublished - 1994

Abstract

The kinetics of reduction of trans-[Ru(tmc)O2]2+ (tmc = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) by iodide has been studied in aqueous acidic solution. The reaction has the following stoichiometry; trans-[RuVI(tmc)O2]2+ + 3I- + 2H+ → trans-[RuIV(tmc)O(OH2)]2+ + I3 -. The rate law is -d[RuVI]/dt = (ka + kb[H+])[RuVI][I-] with ka = 0.041 ± 0.013 dm3 mol -1 s-1 and kb = 18.5 ± 0.2 dm6 mol -2 s-2 at 25.0°C and 0.1 mol dm-3 ionic strength. For ka ΔH‡ = 42.9 ± 9.4 kJ mol-1 and ΔS‡ = -131 ± 40 J K-1 mol-1, while for kb, ΔH‡ = 36.9 ± 2.9 kJ mol-1 and ΔS‡ = -97 ± 10 J K-1 mol-1. A mechanism involving oxygen-atom transfer from RuVI to iodide is consistent with the data.