SYNTHESIS, REACTIVITY AND CATALYTIC METHANE FUNCTIONALIZATION STUDIES OF PYRIDYLPYRROLYL AND PHOSPHINE SUPPORTED IRIDIUM AND OSMIUM COMPLEXES

Methane (CH4) is a potent greenhouse gas, with a short-term global warming potential approximately 80-times greater than carbon dioxide. Owing to the inert and non-polarized C–H bonds in CH4, its catalytic chemoselective functionalization is a longstanding challenge facing both chemical and engineering communities alike. Therefore, robust catalysts for the selective functionalization of CH4 to value-added products under mild conditions is an important research question facing society at large. Chapter 1 introduces the issues of CH4 as a greenhouse gas and provides a perspective on the use of high-throughput experimentation for more resource efficient methods of catalyst discovery. By examining large datasets, comprised of both positive and negative datapoints, the use of machine learning for the discovery and design of new CH4 functionalization catalysts is analyzed. Chapter 2 describes a series of coordinatively unsaturated 16e– [CpIr]2+ complexes supported by either a pyridylpyrrolyl or trimethylphosphine ligand. By varying the electronic profile in [CpIr(3,5-R-PyrPy)Cl] (R = tBu, CF3), an unexpected and reversible change in pyrrolyl coordination is observed upon Cl abstraction. Furthermore, addition of a Lewis acid to [Cp*Ir(PMe3)(k2-OAc)]+ enables the OAc ligand to bindh-1, thereby opening a coordination site for reactivity – wherein we observe and characterize the products of C–B activation. Chapter 3 describes the synthesis, characterization, and catalytic studies of dmpe supported surface organometallic IrI complexes for the chemoselective catalytic borylation of CH4. In this study, a simple grafting of homogeneous organometallic precatalyst (dmpe)Ir(cod)CH3 on amorphous silica enables 2031 TON for CH4 functionalization. Finally, Chapter 4 describes a family of dmpe supported IrI and OsII complexes for the room temperature catalytic borylation of CH4. The mechanism of this catalytic cycle is probed via DFT to help elucidate key insights into this mild and selective transformation.