Date of Award

Spring 2021

Document Type

Restricted Thesis

Terms of Use

© 2021 Mika L. Maenaga. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Chemistry & Biochemistry Department

First Advisor

Christopher R. Graves

Abstract

The development of sustainable catalytic systems is a major effort in green chemistry. Expanding main group chemistry into new catalytic applications offers relatively non-toxic, sustainable, and environmentally conscious alternatives to their heavy metal counterparts. We have focused on the group 13 elements, aluminum and gallium. Stable primarily in the 3⁺ oxidation state, both lack the ability to readily access multiple redox states. One way to overcome this challenge is through the addition of non-innocent ligands which can enable reactivity in their metal complexes in many ways, including actively participating in the forming or breaking of substrate covalent bonds. We report the O–H bond activation of various alcohols via element-ligand cooperative chemistry with aluminum and gallium tripodal tris(nitroxide) [{(2- ᵗBuNO)C₆H₄CH₂}₃N]³⁻ (TriNOx³⁻) complexes. To understand the effect of the different metals on the mechanistic pathway of the O–H bond activation HOR (R = tBu, Ph) by (TriNOx)M (M = Al, Ga), we explored the pathways through DFT calculations. The mechanism of (HTriNOx)M–OR formation was found to be through neutral compounds as opposed to a stepwise deprotonation resulting in a charged intermediate. The strength of the acid, not the difference in catalyst by metal, was shown to drive changes in the mechanism of each reaction pathway. Understanding the mechanistic difference of these O–H bond activations gives us insight into utilizing aluminum and gallium catalysts in similar reactivity as transition metal catalysts.

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