Stable anion radicals based on a triazole-fused furazano[3,4-b]pyrazine scaffold

Abstract

A completely original open-shell scaffold, based on the furazano[3,4-b]pyrazine moiety, has been recently discovered and has already shown certain advantages over mainstay radical blocks. Here, we present a way to synthetically extend this class by changing an oxadiazole moiety into a triazole, yielding triazolo[4,5-e]furazano[3,4-b]pyrazines, thereby unlocking a site for substituents in the scaffold. We also propose new transformation conditions for the key cyclization step of bis(arylhydrazones) to the corresponding 6-aryltriazolo[4,5-e]furazano[3,4-b]pyrazines. The anion radicals, resulting from their easy one-electron oxidation, exhibit good stability and unexpected NIR luminescence.