AER Chemistry Seminar — Vincent Groner

About the event

Title: Examining the Lewis Acid-Base Interactions Between Uranyl Complexes and Various Lewis Acids

Abstract: The reactivity of the uranyl cation ([UO2]2+) is an underdeveloped area of uranium chemistry due to the high stability of the U=O bond, which is resistant to ligand exchange or cleavage. Current research has focused on exploiting the lone-pair electrons on oxygen atom(s) of [UO2]2+ which can act as Lewis base(s) with the goal of functionalizing the U=O bond for organic transformations.  Previous studies have concluded that the Lewis-base strength of the oxygen in [UO2]2+can be enhanced or limited with various ancillary ligands. The electron-donating ligand 2,4-pentadione was shown to promote the interaction between the uranyl oxygen and Lewis acidic bispentafluorophenyl borinic acid, while the strongly electron-withdrawing ligand 3,5-decafluoroheptadione analogue prevented any Lewis acid-base interaction from occurring. Utilizing this Lewis acid-base interaction with trispentafluorophenyl borane and reductive silylation with Et3SiH a readily exchangeable UV-OSiR3 bond was found, with the oxygen originating from the U=O bond when using slightly electron-withdrawing dibenzolymethane ligands. Finally, the Lewis acid-base interaction [UO2]2+ using redox-active iminoquinone ligand 4,6-di-tert-butyl-2-[(2,6-diisopropylphenyl) imino]quinone.  When reacting these [UO2]2+ complexes with either chlorocatecholborane or pivaloyl chloride the U=O bond was functionalized and irreversible cleaved.