Abstract
Ligand derivatization and incorporation of secondary metals are established strategies for tuning the redox properties of inorganic and organometallic complexes, and these strategies have been leveraged in this dissertation to accomplish modulation of the properties of several novel classes of rhodium, chromium, and cerium complexes. Chapter 1 summarizes overarching themes and particular projects presented in this dissertation, while Chapter 2 reviews the foundational elements, methods, and techniques of organometallic electrochemistry that have been used in all of the projects composing the research in this dissertation. Chapters 3-6 describe research on [Cp*Rh] (Cp* = pentamethylcyclopentadienyl) complexes bearing bidentate ligand frameworks for modulation of reactivity and redox properties. Chapters 3 and 4 specifically discuss bidentate hybrid phosphine-imine ligand designs, the reactivity of hydride complexes, and dihydrogen evolution. Chapters 5 and 6 examine the influence of ligand substituents in a dipyridylmethane (dpma) ligand system on the kinetics of a redox-induced ligand rearrangement. Chapter 7 describes a series of electrochemical and spectroscopic studies of a family of chromium complexes that also bear bidentate hybrid phosphine-imine ligands; in this study, we utilized chemical reductants and aluminum reagents for mechanistic interrogation and assignment of the oxidation states accessible to chromium in the absence and presence of aluminum. Finally, Chapter 8 describes the modulation of cerium (IV)/cerium(III) redox chemistry with Lewis acidic secondary metals in a heteroditopic tripodal ligand scaffold developed in this work. The finding shows that installation of mono- and divalent cations near cerium enables systematic tuning of lanthanides for the first time. Taken together, the works described in this dissertation contribute to the areas of electrochemistry, organometallic chemistry, and f-element chemistry through the development of ligand frameworks and utilization of bimetallic effects to modulate the redox chemistry of metal complexes.