Our interest in finding suitable waste forms for the effective immobilization of minor actinides in persistent architectures has led us to explore the molten salt syntheses of Np, Pu, and Am containing materials to study their crystal chemistry. This effort has resulted in several new neptunium, plutonium, and americium containing phases including K3Am(PO4)2, K3AmSi2O7, Ba3Am2(BO<
The formation and cleavage of chemical bonds in catalytic reactions relies on accessible redox processes that are often challenging for base metals such as first row and early transition metals. Bimetallic cooperativity provides a potential solution to this challenge. Leveraging dinucleating phosphinoamide ligands, a series of early/late heterobimetallic Zr/Co compounds have been synthesized and investigated. These frameworks have been shown to support metal-metal multiple bonds and facilitate redox and small molecule application processes.
The conversion of carbon dioxide to fuels is a promising approach to sustainable energy storage. Selective and efficient reduction of CO2 to fuels (or fuel precursors) relies on advanced catalysts. Guided by the detailed mechanistic insights available from studies of molecular catalysts, we are developing broad strategies and structural design principles for CO2 reduction reactions. Selective CO generation is accomplished with ruthenium and iron complexes that pair a redox-active supporting ligand with a strongly donating ligand featuring an N-heterocyclic carbene (NHC).
Paramagnetic Ni and Pd complexes have been proposed to play an important role in a number of C-C and C-heteroatom bond formation reactions, as well as a series of oxidative and reductive transformations. In this context, a series of uncommon mononuclear Pd(III) complexes have been synthesized and their oxidative reactivity was investigated. In addition, organometallic Ni(III) complexes relevant to cross-coupling reactions have been isolated and their catalytic reactivity was studied in detail.
Proton-coupled electron transfer (PCET) is a central principle for catalytic hydrogen and CO2 transformations. In this seminar, I will discuss how internal factors of metal–ligand identity, coordination geometry, and spin states interact with external influences such as pKa of proton donors and applied potentials to shape PCET pathways. Our studies with Co complexes show that spin interactions critically govern electron transfer, while investigations of Fe complexes reveal how maintaining the low spin states enables rapid, efficient multi-electron processes.