Reverse pulse polarography for EC processes. Electrochemistry of 1,1′-trimethylene-bis-(4-carbomethoxypyridinium) ion

J. Hermolin*, D. Talmor, E. Kirowa-Eisner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The 1,1′-trimethylene-bis-(4-carbomethoxypyridinium) ion (3++) is reduced in tetrabutylammonium perchlorate (TBAP)+CH3CN at the dropping mercury electrode to the biradical 3·· in an EC-type reaction, consisting of a reversible charge transfer 3+++2e- = 3op, followed by intramolecular cyclization (3op being the open form of the biradical) to cyclomers. Depending on the time scale, different cyclomers are formed: in the sub-millisecond time range, the coupled chemical reaction results in the reversible formation of fast forming species 3ff, cyclomers with π-type interactions (cis-cyclomer B). In the time range of seconds, the slow forming species 3sf with σ-type interactions (trans-cyclomer) are dominant. The forward and backward rate constants of the reaction 3ff = 3sf are determined by the reverse pulse polarographic method: kf = 3.0 s-1, kb = 1.0 s-1. In the presence of metallic ions, 1:1 biradical-metal complexes are formed reversibly. The stoichiometry and formation constants are determined by the reverse pulse polarographic method: K3Li/op = 1.2×104 l mol-1; K3Mg/op = 1.1×105 l mol-1.

Original languageEnglish
Pages (from-to)148-153
Number of pages6
JournalJournal of Electroanalytical Chemistry
Volume491
Issue number1-2
DOIs
StatePublished - 8 Sep 2000

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