Phospho-Redox

The overarching objective of this proposed project is to construct the experimental physical, thermodynamic, and mechanistic foundation for the development of new and broadly applicable class of odd-electron redox active nonmetal catalysts based on phosphorus. By bringing together researchers from the US and France with complementary expertise in organophosphorus synthesis and catalysis (Radosevich) and photochemistry and mechanistic analysis (Lahkdar), this collaborative effort will realize a ‘radical’ new direction in catalysis using earth-abundant elements. The proposed activities will be organized along two lines of inquiry that each bring the opportunity for significant collaborative intellectual contributions. Aim 1 will synthesize a series of redox active phosphines in which the role and magnitude of substituent effects on the redox potential and spin distribution of open-shell phosphoniumyl intermediates will be delineated. With reliable access to persistent compounds of this type, we will acquire a detailed, experimental quantification of the impact of redox level tuning and electronic overlap on spin delocalization in main group catalysts and realize new modes of organic substrate transformations not previously accessible. Aim 2 will develop redox active, odd electron phosphine oxides as H-atom transfer reagents and catalysts. We will quantify the establish trends in experimental bond enthalpies for open shell phosphine oxides, and advance an understanding of persistent radicals in coupled proton-electron transfer organic methodology. The major output of this research will be the establishment of the necessary fundamental science and conceptual blueprint that will enable open shell p-block catalysis to be regarded on a complementary but equal footing with established modes of catalytic activation.