Model Compounds of Trivalent and Tetravalent Lanthanide Metal Complexes for Elucidating Rational Reactivities

In order to understand the reactivity of lanthanide metal cations, we developed model compounds of cerium(III) acetylide complexes and strongly stabilized Ce(IV) complexes. Using a framework with aryloxide ligands including pendant amine groups, heterobimetallic cerium(III) complexes with one coordination site, one alkali metal cation and three supporting ligands were prepared. Coordination of an acetylide functional group resulted in the first structurally characterized cerium(III) acetylide complex. Using the stabilized cerium(III) acetylide complex, carbonyl addition reactivity was observed, where the resulting products were fully characterized. A redox non-innocent ligand framework was developed and shown to stabilize an unusual oxidation states. The redox active, multidentate ligands were namely applied to cerium(IV) and other lanthanide metal cations. Electrochemical analysis revealed reversible redox waves, speaking to their stability upon oxidation. Isolated metal complexes of the redox active nitroxide ligand, obtained from chemical oxidation reactions, were characterized by X-ray crystallography, confirmed the electrochemical assignment.