N , N′ ‐Ethylene‐Bridged Bis‐2‐Aryl‐Pyrrolinium Cations to E ‐Diaminoalkenes: Non‐Identical Stepwise Reversible Double‐Redox Coupled Bond Activation Reactions

Abstract

We present here a stepwise reversible two-electrontransfer induced hydrogen shift leading to the conversion of a bis-pyrrolinium cation to an E-diaminoalkene and vice versa.Remarkably, the forward and the reverse reaction, which are bothreversible, follow two completely different reaction pathways.Establishing such unprecedented property in this type of processeswas possible by developing of a novel synthetic route towards thestarting dication. All intermediates involved in both the forward andthe backward reactions were comprehensively characterized by acombination of spectroscopic, crystallographic, electrochemical,spectroelectrochemical, and theoretical methods. The presentedsynthetic route opens up new possibilities for the generation of multi-pyrrolinium cation scaffold-based organic redox systems, whichconstitute decidedly sought-after molecules in contemporarychemistry.