Electron Spin Resonance and Electrochemical Studies of Some Mesoionic and Neutral 1,2,3,4-Oxa- and -Thiatriazoles and Their Alkylation Products

✍ Scribed by Friedrich Stuhlmann; Günther Domschke; Anton Bartl; Andreas Neudeck; Andreas Petr; Ladislav Omelka

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 477 KB
• Volume: 35
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199702)35:2<124::aid-omr42>3.0.co;2-4

✦ Synopsis

Voltammetric studies of mesoionic 1,2,3,4-oxa-and -thiatriazoles conÐrmed that the former may be reduced irreversibly at potentials between Ô1.19 and Ô1.73 V vs. ferrocene in acetonitrile at scan rates between 0.05 and 1000 mV s-1, whereas the latter are reduced reversibly under the same conditions. The corresponding radical anions were examined by ESR spectroscopy. Cationic alkylation products of the above compounds showed di †erent electrochemical behaviour depending on the character of the heterocyclic ring. 1,2,3,4-Thiatriazolium ions were reduced reversibly. All coupling constants of the resulting neutral radicals were fully assigned using isotopic labelling. A cation with an 1,2,3,4-oxatriazolium ring reacted by cleavaging of an exocyclic CÈS bond on electron uptake. The resulting alkyl radical was spin-trapped.