Facilitating Multi-Electron Chemistry in the F-Block Using Iminoquinone Ligands

The chemistry of the f-block is relatively unknown when compared to the rest of the periodic table. Transition metals and main group elements have enjoyed thorough study and development over the last 200 years, while many of the lanthanides and actinides weren’t even discovered until the 1940’s. This is troublesome, as knowledge of these elements is critical for environmental, industrial and technological advances. Understanding bonding motifs and reactivity pathways is fundamental to advancing the field of f-block chemistry. The use of redox- active ligands has aided in the construction of new bonding modes and discovery of new reaction pathways by providing electrons for these transformations. A particularly successful partnership is formed when redox-active ligands are combined with lanthanides, as these elements are usually considered redox-restricted. A series of lanthanide complexes featuring the iminoquinone ligand in three oxidation states will be discussed. The use of the ligands as a source of electrons for reactivity is also described, with new bonding motifs for lanthanides being realized. The iminoquinone ligand can also serve to break bonds. The uranyl (UO22+) ion is notoriously difficult to handle due to its strong U-O multiple bonds. To overcome this, we developed a series of uranyl complexes and studied the ability of the iminoquinone ligand to serve as an electron source for reduction of uranium, with concomitant U-O bond cleavage.