New Paradigms in Main Group Element Assembly and Catalysis

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Overview. Main group elements are Earth abundant and form essential components of modern electronics, LEDs, and household products. In this proposal we build upon our research team's prior experience in fundamental inorganic chemistry to address the following pressing questions: a) Can we deposit conducting or insulating components for advanced optoelectronic applications without the need for highly toxic chemicals or harsh conditions? b) Can we coax inexpensive main group elements into performing catalytic transformations previously reserved for expensive metals? We use carbon-based ligands to intercept reactive hydrogen-rich main group species, termed hydrides. These hydrides are often found as free entities in exotic locals such as in interstellar space or at high temperatures. Our work seeks to harness the reactivity of hydrides to accomplish metal-free catalysis or advanced material synthesis under mild conditions. NMR, IR and UV-vis spectroscopy are used to monitor reaction progress and X-ray crystallography to identify new molecular structures. Gel permeation chromatography and thermal analyses (TGA/DSC) allow us to characterize polymers, while computational methods serve as vital predictive tools to evaluate potential reaction paths. We collaborate with experts worldwide and such interactions will help us design/test new batteries and olefin polymerization catalysts. Our proposed program is grouped along three interconnected themes: 1. Mild Deposition of Conductors and Insulators. Traditionally electroactive components have been incorporated into devices using high-temperatures and toxic gaseous precursors. However the harsh nature of these methods places a limit on the types of materials that can be deposited. We will take advantage of the rapid, solution-based, formation of various element hydrides (such as germanium(II) dihydride) and their mild conversion into pure element films, nanomaterials and polymers for use in next generation solar cells and batteries. We will also develop precursors to the highly sought insulator boron nitride, currently prepared at >1500 °C. 2. Non-innocent Lewis Acidic Ligands for Catalysis. We will explore a new class of ligand that combines a high degree of steric coverage with the advantageous reactivity inherent to electron deficient (Lewis acidic) groups. The close proximity of these electron deficient ligands to reactive main group centers should encourage cooperative interactions, leading to improved catalytic activity. 3. Anionic N-Heterocyclic Olefins. We recently prepared a series of carbon-based ligands termed anionic N-heterocyclic olefins (aNHOs). We will harness the donor ability of aNHOs to access a series of low-coordinate main group compounds that are pre-designed to act as olefin polymerization catalysts (a billion dollar industry). These aNHO ligands will also be used to tackle a long-standing challenge in industry: the mild catalytic formation of ammonia from abundant nitrogen gas.