A Redox-Active Frustrated Lewis Pair for the Activation and N-O Scission of Nitrosonium Cations

Frustrated Lewis pairs (FLPs) have revolutionized main-group chemistry by enabling reactivity traditionally associated with transition metals. However, existing FLP systems are predominantly restricted to two-electron heterolytic or homolytic bond activation mechanisms. In this work, we present a phosphine functionalized with a peripheral redox-active phenothiazine moiety and explore its unique behavior within an FLP framework. The resulting FLP exhibits unprecedented reactivity, allowing for the activation of the highly oxidizing nitrosonium cation with subsequent N-O bond scission. This reaction is facilitated by the redox-active functionality, first being oxidized by a single electron, then producing a reactive FLP that activates NO, resulting in an overall 3-electron bond activation. This novel transformation underscores the potential of incorporating redox-active groups to expand the scope of FLP chemistry, paving the way for new avenues in main-group bond activations.