Synthesis, Characterization, and Reactivity of Low Valent Uranium Alkyls

Sara A Johnson, Purdue University

Abstract

Transition metal alkyls play an important role in organometallic chemistry. Thus, exploration of uranium alkyls, which are relatively rare, has a high potential for new transformations. Homoleptic uranium(IV) tetra(alkyls) are difficult to isolate, due to their notorious instability at room temperature. Recently, tetrabenzyluranium, U(CH2C6H5) 4, was synthesized, characterized, and showed reductive elimination chemistry with the use of redox active α-diimine and iminoquinone ligands. A family of homoleptic tetra(alkyls) with different para- and meta-substituted benzyl ligands has been explored to determine the generality of the synthetic method and the effect of ring substitution on complex stability and reductive elimination capabilities. The kinetics of the reductive elimination reaction from the uranium(IV) tetra alkyls induced by redox active ligands has been measured to better understand the rates of this process. While uranium(IV) alkyls are rare and interesting, low valent uranium(III) alkyls examples are even more uncommon. By using large tridentate hydrotrispyrazolylborate type ligands to stabilize the reactive uranium metal center a family of uranium(III) alkyls could be synthesized. These compounds feature benzyl type ligands which have been shown to bind in different hapticities. The increased hapticity of the ligand offers increased stability by creating a more coordinatively saturated metal center. These low valent uranium alkyls have the potential for unique reactivity and can be used as precursors to uranium multiple bonds, such as imidos, oxos and sulfidos.

Degree

Ph.D.

Advisors

Bart, Purdue University.

Subject Area

Chemistry|Inorganic chemistry

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