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.