Noble metal catalysts, such as Shvo’s diruthenium bridging hydride, have become commonplace in the modern world. While these catalysts are often highly active, they are costly due to the low natural abundances of platinum-group metals and for the same reason are also unsustainable in the long term. Therefore, catalysts based on earth-abundant metals with similar reactivities to noble metal catalysts are desirable. Iron, being the second most abundant metal in the earth’s crust, is significantly less expensive and more sustainable than the noble metals. Knölker’s iron hydride has a similar structure to Shvo’s catalyst, containing Fe instead of Ru, and has also been shown to have a similar reactivity profile. Various studies have shown that the structure and electronics of the cyclopentadienone influence the activity of the catalyst, and our focus was on how the electronics of the cyclopentadienone impact the activity of the catalyst. Tetraarylcyclopentadienone iron tricarbonyl catalysts bearing electron-donating or electron-withdrawing groups were synthesized and characterized by proton and carbon NMR spectroscopy. The catalytic activities of these catalysts were studied in the oxidation of 4-phenyl-2-butanol and the reduction of acetophenone, and gas chromatography was used to monitor the progress of the reactions. Electron-rich catalysts<b> </b>outperformed those bearing electron-withdrawing groups, which suggests that increasing the electron density of the iron center positively impacts the performance of the catalyst. The structural impacts of modifying the electronics were inspected using IR spectroscopy and cyclic voltammetry. IR spectroscopic studies showed no clear pattern between the reactivity of the catalyst and the strength of the CO bond stretches. The cyclic voltammograms revealed non-reversible oxidation and non-reversible reduction processes for all of the iron compounds.

Synthesis, kinetic, and electronic studies of (3,4-diarylcyclopentadienone)iron tricarbonyl compounds

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.