PhD, University of Cincinnati, 2017, Arts and Sciences: Chemistry

The development of new catalysts for the reduction of carbon dioxide is of utmost importance to both limit the harmful greenhouse gas as well as to provide usable C1 feedstock chemicals. One method to reduce this CO2 is through the use of a metal hydride complex. Of these metal complexes, nickel POCOP pincer hydride complexes have been highly successful at catalyzing the reduction of carbonyl functionalities. Although these catalysts are effective at catalyzing this reduction, there are few processes to make these hydrides. Additionally, not much is known about which factors will improve catalytic reduction or what other reactions they can catalyze. Nickel chloride complexes bearing POCOP pincer ligands were easily synthesized using a microwave reactor. Through this methodology nickel POCOP pincer chloride complexes can be made in as little as 5 minutes in very high purities and yields. Nickel complexes with iPr, cPe, Cy, Ph, and tBu substituents on the phosphorous atoms can all be synthesized using this method. Additionally, palladium chloride complexes bearing isopropyl substituted POCOP ligands can be made. This method was also found to greatly limit the solvent needed to make these complexes. Alternative routes to synthesize nickel hydride complexes is an important problem due to the harsh methods used to synthesize them. To explore an additional method for hydride synthesis, nickel fluoride complexes bearing POCOP pincer ligands were synthesized. These complexes can be easily converted to hydride complexes using silanes or boranes. The factors that influence a metal hydrides ability to reduce CO2 were investigated. To determine which factors had an impact on the reduction of CO2 to formate complex, a series of nickel hydride and formate complexes were synthesized. The complexes were tested to determine the relative thermodynamic favorability for the reduction of CO2 to formate. Complexes bearing more electron donating ligands were found to be (open full item for complete abstract)

Committee: Hairong Guan Ph.D. (Committee Chair); William Connick Ph.D. (Committee Member); Allan Pinhas Ph.D. (Committee Member) Subjects: Chemistry