New Hydrocarbon-Stabilized Metal-Atom Reagents

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The Research award in the Inorganic, Bioinorganic and Organometallic Chemistry Program supports the work of Professor John E. Ellis at the University of Minnesota-Twin Cities for research into previously unexplored areas of low valent transition metal chemistry. Objectives include defining the limits of "superreduced" transition metal chemistry and providing new understanding of the reduction of coordinated ligands. Naphthalene, anthracene, and other polycyclic aromatic hydrocarbon,or polyarene, complexes containing transition metals in formal oxidation states that are unprecedented, such as Sc(I-), V(II-), and Cu(I-), or very rare, such as Hf(0, II-), Ta(I, 0), and Ni(I-, II-), will be prepared by reduction of metal halides or related precursors in the presence of these hydrocarbons. The new compounds will be isolated and fully characterized whenever possible. Anionic polyarene-stabilized complexes promise to be of particular interest as unique storable sources of "naked" atomic metal anions, M(Z-). Their reactions with dinitrogen, carbon monoxide, isocyanides, phosphanes, and other acceptor ligands will be explored as a route to hitherto unknown classes of low valent metal complexes. The development of conventional routes to new hydrocarbon-stabilized metal-atom reagents will enable access of such highly-reactive species by other investigators, who do not have access to the specialized and expensive metal-vapor reactor apparatus originally required for the preparation of related species. This project is also important in the education, training, and professional development of a new generation of scientists and educators, including undergraduate and graduate students, visiting faculty, and other post-doctoral associates, where participation by minorities and women is particularly encouraged. Polyarene metal complexes are possible reagents for nitrogen fixation, catalysts for new polymers of unsaturated organic and inorganic species and precursors to novel polymetallics. This project endeavors to develop facile and reproducible routes to new labile hydrocarbon complexes and employ these species as reagents for a general investigation of the chemistry of transition metals in previously unknown or rare formal oxidation states. In this fashion significant contributions to our fundamental understanding of transition metal chemistry are anticipated.