Directing Structure and Reactivity in Synthetic Uranium Complexes

The coordination chemistry of uranium is not well understood. This fact is at the crux of all issues in modern synthetic uranium chemistry. Imposing simple design principles including steric pressure and coordinative saturation have proven most effective for the rational synthesis of uranium complexes. In this work, the effect of minor perturbations to the electronic structure on the gross molecular structure is investigated. Intramolecular non-covalent interactions are shown to influence the primary and secondary coordination sphere at uranium ions. Forces common in supramolecular assembly similarly control the orientation of ligands about the metal center. Insight is provided into the inverse trans influence, a thermodynamic phenomenon that preferentially stabilizes reactive uranium-ligand bonds in a preferred axial bonding orientation. Leveraging the inverse trans influence allowed for the first reported synthesis of uranium(VI)-alkyl and -acetylide complexes, and the establishment of an inverse trans influence ligand series. The role of covalency in stabilizing uranium-ligand bonds is explored.