WIBS Talk: Non-aqueous Uranium Chemistry: Stabilizing Six Oxidation States

James Boncella will be presenting a 20-30 minute talk (abstract below) at 6:30 pm. Socialization sarts at 6:00 pm with an informal discussion and socialization the remainder of the evening. A Zoom option is available (see below).

Abstract: In this talk, I will discuss our research into the synthesis of uranium complexes in non-aqueous media. Unlike aqueous solutions where the major species are U(VI), as the uranyl ion (UO2)2+, and U(IV), non-aqueous media allows the formation of U complexes in formal oxidation states ranging from U(I) to U(VI).

We have been investigating these complexes to assess the involvement of the 5f valence orbitals in actinide-ligand bonding because differences in 4f vs 5f participation in M-L bonding are believed to play an important role in actinide/lanthanide separation chemistry. Our long-standing interest in high-valent U(VI-IV)-Imido and -bis(imido) complexes (where U imido is the U=NR functionality) originally focused our attention on 5f participation in the formation and stabilization of U=NR multiple bonds. Changes in the reactivity of U-imido complexes track with 5f orbital participation in the U=N multiple bond as the formal oxidation state of the metal center changes.

More recently, our attention has been focused on interactions between low-valent U and arenes and other unsaturated hydrocarbon ligands. I will discuss our use of the chelate effect to bring an unsaturated hydrocarbon ligand into close-proximity to a low-valent U center to facilitate the U-hydrocarbon interaction. This strategy has resulted in the synthesis of U(II) and formally “U(I)” arene complexes. The reactivity of these new molecules will be discussed as well as the uranium 5f-to-arene-p*  d-back-bonding interactions that are essential in stabilizing these compounds.

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