Synthesis and reactivity of high-valent copper complexes and the design of copper monooxygenase model complexes

Abstract

Copper plays a vital role in various enzymatic and catalytic transformations. Specifically, copper-oxygen and high-valent copper species are implicated as intermediates in oxidations by metalloenzymes and catalysts. In order to study the nature and the role of copper in these transformations, copper model complexes have been sought after and investigated for their properties and reactivities. This thesis describes several such copper model complexes. Chapter 1 outlines the biological precedence of copper-oxygen complexes in a monooxygenase enzyme and a class of copper complexes that mimic the monooxygenase active site. Additionally, the literature relevant to high-valent copper complexes discussed herein is reviewed. In chapter 2, the development of two biomimetic, monoanionic ligands and their copper complexes is discussed. The characterization of the ligands and complexes and efforts to access copper-oxygen complexes bearing the monoanionic ligands are shown. Chapter 3 details the generation of a new high-valent copper-nitrite complex and its oxidative proton-coupled electron transfer (PCET) and anaerobic phenol nitration reactivity. Mechanistic considerations for the unusual anaerobic phenol nitration are made. Lastly, chapter 4 describes the synthesis and characterization of two copper-amidate complexes and the generation of their high-valent counterparts. The PCET reactivity of the high-valent copper-amidate complexes are contrasted with each other and previous high-valent copper-oxygen complexes. The results from the projects described herein provide insights into copper coordination chemistry, electronic structure, and reactivity, which helps augment the knowledge of copper enzymes and catalysts.