Rational Synthesis and Characterization of Tetravalent Cerium Coordination Compounds

In order to expand the synthetic chemistry of molecular cerium(IV) complexes, we explored chemical oxidation of cerium(III) starting materials and we functionalized cerium(IV) precursors using protonolysis, metathesis, and silyl halide exchange reactions. Using these synthetic strategies, we isolated two families of cerium(IV) coordination compounds and compared the spectroscopic and electrochemical consequences of varying ligand coordination to the cerium(IV) cation. Despite the highly ionic nature of the metal ligand bonds, we found that properties of these cerium(IV) complexes were sensitive to the local coordination environment. We also explored the properties of lanthanide complexes in macrocyclic tetraazaannulene ligand environments and demonstrated that the secondary coordination sphere could be used to control the properties of these complexes. In this way, we demonstrated a redox induced single crystal to single crystal transformation, hydrogen atom transfer upon oxidation of a cerium(III) compound, and slow paramagnetic relaxation in late lanthanide double-decker complexes.