Synthesis of Pd(II) Complexes Containing Redox-active Dipyrrolic and Tripyrrolic Ligands

Abstract

Redox-active ligands represent a large class of molecules that have multiple applications in the field of catalysis. This is due, in part, to their ability to undergo redox transformations independently of the metal center; thus, expanding the redox capabilities of many transition metals. Recently the Tomat lab examined the coordination chemistry of two linear oligopyrroles, propentdyopent and tripyrrindione, to divalent transition metals. It was determined that each of these ligands were capable of hosting redox events and were therein considered to be redox-active. The focus of this thesis is to expand upon this work and explore the properties of these ligands. Chapter 1 presents and introduction to redox-active ligands with a focus on applications in catalysis, while also discussing the relevance to oligopyrrolic ligands this area. Chapter 2 focuses on the dipyrrindione ligand propentdyopent, and details the synthesis of a series of heteroleptic PdII complexes which contain intramolecular hydrogen bonds. The effect of these hydrogen bonds on the redox potential of the propentdyopent scaffold will be examined. Chapter 3 describes synthetic modifications to the tripyrrindione ligand through alkylation of the C1 and C14 carbonyl groups, and how these modifications effect the resulting PdII complex’s electrochemical profile. Chapter 3 will also explore the reactivity of the tripyrrindione ligand with nitriles under anaerobic conditions.