Lonergan, MarkHurst, Michael2022-05-102022-05-10https://hdl.handle.net/1794/27161The activation of silanes by transition metals is a crucial step in many transformations, including hydrosilylation, cross-coupling, and carbene insertion. Palladium is a common metal in catalysis and its activity is usually ascribed to Pd(0) species. Yet, the fundamental oxidative addition of Pd(0) to silanes has not been studied systematically or mechanistically. Thus, we undertook studies to probe the oxidative addition of Pd(0) to Si–H and Si–X bonds, focusing on elucidating mechanisms and uncovering trends in reactivity that will contribute to catalytic development and optimization.Chapter 1 motivates the study of oxidative addition to silanes, including a discussion of current challenges and potential benefits. Chapter 2 describes our work on elucidating the mechanism of oxidative addition of Pd(0) to Si–H. Unique insights into the reaction with tertiary silanes led to our proposal of a concerted mechanism for oxidative addition. Furthermore, energy barriers for each step in the proposed mechanism were experimentally determined to support this hypothesis. Chapter 3 extends upon work in Chapter 2 to explore the electronic influence of silane substituents in their reaction with Pd(0). A pronounced electronic effect is observed to favor silanes with electron-poor groups. Chapter 4 focuses on understanding the steric influence of silane substituents in oxidative addition. A side-by-side comparison of reaction energy barriers with silanes of varied steric hindrance suggests that differences in reactivity arise primarily from thermodynamic, not kinetic, factors. Chapter 5 utilizes silyl palladium hydrides as catalysts in alkyne hydrosilylation, showing good agreement with trends in oxidative addition. Mechanistic studies suggest a complicated mechanism in which intermediate equilibria impact the reaction. Chapter 6 reports on the oxidative addition of Pd(0) into Si–X bonds of halosilanes (X = Cl, Br, I). Mechanistic proposals and evidence are presented for the reaction with three distinct Pd(0) complexes to indicate disparate activation pathways for each. Chapter 7 details our efforts to use fundamental understanding of oxidative addition in synthesizing a new class of heterogeneous catalyst. Experimental methods for the formation of surface silyl palladium hydrides and their role in catalysis is presented. This dissertation includes previously published and unpublished coauthored material.en-USAll Rights Reserved.catalysismechanismorganometallicorganosiliconoxidative additionpalladiumElectronic Thesis or Dissertation