Date of Award

2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Chemistry

First Advisor

Eric J. Schelter

Abstract

Organometallic compounds with a multiply bound imido ligand have been extensively studied as intermediates in catalytic transformations. While the examples of d-block transition metal imido compounds are ubiquitous, early lanthanide and actinide compounds are more rare. There is a long-standing interest to improve understanding of their chemical behaviors and electronic structures. This dissertation presents work on several aspects of f-element imido chemistry, including reactivity, electronic structures, and photophysical properties. Cerium (IV) imido compounds supported by a tripodal hydroxylaminato ligand framework were used to activate small molecules with polar bonds, such as carbon dioxide, organic isocyanates, ketones, and others. Reaction products were isolated, affording insights into reaction mechanisms and comparisons with d-block transition metal and actinide imido complexes. Electronic structures of cerium (IV) oxo and imido compounds were investigated using XAS spectroscopy, magnetic measurements, and DFT calculations, revealing single-reference ground states and significant temperature-independent paramagnetism. This study improved understanding of ligand impact on the electronic character of the ground state of cerium (IV) organometallic compounds. It was also found that the cerium (IV) imido compounds exhibited no solution-state luminescence, while isostructural thorium (IV) imido compounds were luminescent. By systematically varying the para-substituents on the aryl-imido ligand based on their electron donating and withdrawing ability, a series of thorium imido compounds was prepared, and their photophysical properties were measured. All the thorium(IV) compounds emitted in the blue and the ultraviolet region. Rationalizing the results with DFT calculations, we proposed the role of different radiative transitions and their relative energies in the observed luminescent behavior.

Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Included in

Chemistry Commons

Share

COinS