Secondary Interactions in Transition Metal Catalysis: Metal-Ligand Cooperativity and Beyond

As our global population continues to grow and demand more resources, development of more advanced methods of chemical production and catalysis in an efficient manner are paramount. One such route to advancing catalysis in transition metal chemistry is to utilize not only abundant, inexpensive first-row transition metals, but also utilize more complex means of controlling chemistry around these metal centers. One of the principal challenges to overcome with first-row transition metals is their propensity to perform single-electron transformations that are difficult to control in terms of selectivity and efficiency. Our group has begun developing new methods and new ligand scaffolds aimed at influencing the reactivity of transition metal catalysts. First, new means of metal-ligand cooperative chemistry are being explored using geometrically-constrained phosphorus centers as ligands bound to first-row metal centers. These unique phosphorus sites exhibit a property known as biphilicity, meaning they may behave either as an electrophile or nucleophile depending upon factors such as physical geometry and nature of the metal center they are bound to. Complexes of Fe and Co have been synthesized which are reactive towards small polar bonds such as alcohols, water, and carbon dioxide. In addition to this, an exciting new area of inorganic catalysis lies in the use of an oriented external electric field to alter properties of the transition metal center. We aim to develop a deep understanding of how this phenomenon can occur at a transition metal to influence fundamental inorganic reactions such as ligand exchange, Lewis acidity, and redox properties. A combination of characterization techniques, electrochemical analysis, and vibrational sum frequency generation are our tools to explore this chemistry.