RUI:CAS: New Ligand Platforms for the Synthesis and Study of High-Spin Iron(I) Dinitrogen Complexes

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With this award, the Chemical Synthesis Program of the NSF Division of Chemistry is supporting the research of Professor Paul J. Fischer in the Department of Chemistry at Macalester College to develop new iron compounds that bind nitrogen gas. Comprising nearly 80% of air, nitrogen gas is inert toward most chemical reactions. Because of this inertness, nitrogen resists incorporation by reductive chemistry into useful nitrogen-rich components of fertilizers and pharmaceuticals. The goal of this project is to discover new approaches to enhance the reactivity of nitrogen. The specific concept involves converting nitrogen gas into compounds containing iron. Indeed, Fischer’s research program has identified a family of organic compounds that bind iron, allowing it to activate gaseous nitrogen. The research is being conducted by Professor Fischer and undergraduate students in an environment that fosters diversity by including women and members of groups underrepresented in chemistry. Through this research, the project is providing hands-on training to participants in advanced organic and inorganic chemistry. Student coworkers are prepared for pursuing STEM (science, technology, engineering, and mathematics) careers in academia, industry, or federal laboratories.This project contributes to the "grand challenge" of the development of catalytic/stoichiometric reactions for the manipulation of iron-dinitrogen complexes in a quest to uncover new pathways for N2 functionalization. A family of terminal high-spin iron(I) dinitrogen complexes are targeted. These new complexes allow systematic study of variables affecting the iron-bound dinitrogen ligands in trigonally coordinated and modulated weak ligand fields. A variety of supporting ligands will be examined, with particular emphasis on the pyrazolate motif. Particular attention is paid to the reduction potentials of the new complexes. This project will also explore the reactivity of terminal iron(I) dinitrogen complexes with respect to dinitrogen substitution with diamagnetic and paramagnetic ligands. Additions of organic radicals to terminal dinitrogen ligands will be investigated as one pathway to organic nitrogen products. The functionalization of an iron-coordinated terminal dinitrogen ligand by radical addition would represent an exciting new pathway for iron-mediated dinitrogen reactivity. The research program draws participants from a diverse campus community, providing them with practical, hands-on training in laboratory operations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.