Hydrogen-Atom Attack on Methyl Viologen in Aqueous Solution Studied by Pulse Radiolysis

S. Solar, W. Solar, N. Getoff, Jerzy Holcman, Knud Sehested

    Research output: Contribution to journalJournal articleResearchpeer-review


    Using hydrogen at high pressures of up to 150 bar (0.12 mol dm–3 H2) as an OH scavenger in aqueous MV2+ solutions (pH 1) it is possible to differentiate between two kinds of transient formed simultaneously by H-atom attack on methyl viologen. One of them is assigned to an H adduct on the N atom, MV˙+H+(k= 3.1 × 108 dm3 mol–1 s–1), with absorption bands identical to those of the radical cation, MV˙+, but with ε392.5= 3200 m2 mol–1 and ε600= 1100 m2 mol–1. The MV˙+H+ species deprotonates with k= 2 × 104 s–1, forming the long-lived radical cation, MV˙+. The second type of transient produced, with k= 2.9 × 108 dm3 mol–1 s–1, is attributed to an H-adduct on the ring carbon, MV˙2+H, with ε310= 570 m2 mol–1 and ε470= 920 m2 mol–1, decaying by second-order kinetics with 2k=(6.0±1)× 108 dm3 mol–1 s–1. The formation of MV˙+ by electron transfer from the propan-2-ol radical has been reinvestigated (pH 0–7); its absorption spectrum does not change in this pH range.
    Original languageEnglish
    JournalJournal of the Chemical Society - Faraday Transactions
    Issue number11
    Pages (from-to)2929-2934
    Publication statusPublished - 1984


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