PhD, University of Cincinnati, 2021, Arts and Sciences: Chemistry

Cyclopentadienone/hydroxycyclopentadienyl metal complexes have been of great interest to the homogenous catalysis community for their application as bifunctional hydrogenation/dehydrogenation catalysts. The stable pairing of a Lewis-acidic/basic site next to a reactive hydride or metal center creates a catalytic ‘pocket' that can stabilize reaction transition states. Group 8 cyclopentadienone metal complexes have been extensively studied and applied to numerous organic and inorganic transformations; however, the reactivity of group 7 and 9 cyclopentadienone complexes remain comparatively less understood. Additionally, cyclopentadienone complexes have primarily been studied as standalone metal complexes, and only recently has interest in their application to bimetallic and tandem catalytic reactions emerged. Here, I will present research into newly synthesized cyclopentadienone metal complexes and their unique reactivities. Cobalt cyclopentadienone complexes have been reported in the literature; however, their synthesis has been plagued by poor yields and unwanted side products and their applications remain sparse. Novel cobalt(I) cyclopentadienone complexes were synthesized and their unique reactivity was studied. These compounds showed fast hydride transfer reactivity with triphenyl carbenium tetrafluoroborate in acetonitrile, transferring the acidic OH proton and two electrons in an unusual umpolung type reaction. This reaction was shown to be highly sensitive to solvent conditions, ligand backbone and the presence of exogenous bases and electron donors, giving some insights to its mechanism. The hydride transfer reaction was optimized to yield a class of previously uncharacterized cationic cobalt(I) cyclopentadienone complexes which were shown to be highly diversifiable with three labile coordination sites. These newly synthesized cationic cobalt complexes were screened for their reactivity in organic transformations. Manganese-based cyclopentadienone compl (open full item for complete abstract)

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