Proton-coupled electron transfer oxidation of O–H bond by the N-radical cation of Wurster's blue salt (TMPDA˙+)

Abstract

Here, we report the proton-coupled electron transfer reaction between TEMPO-H and Wurster's blue salt (TMPDA˙⁺). TMPDA˙⁺ could abstract a hydrogen atom from 2,2,6,6-tetramethyl-1-hydroxy-piperidine (TEMPO-H) via concerted electron–proton transfer and displayed a large KIE (7.05 ± 0.07 at 298 K). This work shows that a nitrogen-centered radical cation (R₃N˙⁺) such as TMPDA˙⁺ is more than a weak single-electron oxidant, and can also be an effective PCET reagent for oxidative bond activation.