Chemistry Proposal Defense — Austin Vezina, PhD Student

About the event

Title: Investigation of the Unique Electronic Structures of Cp2U(NR)2 and Cp2U(NR)(O) Complexes

Abstract: Uranium has a significant impact on the environment because of its radioactivity and the fact that its most stable form, uranyl ([UO2] 2+), has high mobility in groundwaters and soil. The uranyl cation features two mutually trans oxo ligands (formally triple bonds) and is extremely robust and inert due to significant covalent bonding from the 5f orbitals. As a result of this, uranium coordination chemistry was often limited to study of the uranyl cation bound to a variety of equatorial ligands. Uranium research is particularly relevant due to its environmental impacts, role in the nuclear fuel cycle, and its potential as an analogue for more hazardous transuranic actinides. Investigation of the unique electronic structures of uranium complexes is vital to a more fundamental understanding of uranium chemistry. Despite the challenges associated with uranyl, uranium research has advanced rapidly within the last century with the advantage of non-aqueous synthetic chemistry allowing for deviation from the uranyl moiety. One specific area that has received considerable attention in the last two decades is the investigation of the analogous, isoelectronic uranium bis(imido) moiety, [U(NR)2] 2+ . The proposed work seeks to investigate uranium-ligand multiple bonding and electronic structure via DFT and solid-state NMR spectroscopy of a new series of Cp2U(NR)2 complexes (Cp = C5H5), Cp2U(NR)(O) complexes, and ultimately, Cp2UO2 complex featuring indisputable cis-dioxo ligands.