Theses and Dissertations

ORCID

https://orcid.org/0000-0001-8422-069X

Issuing Body

Mississippi State University

Advisor

Hollis, T. Keith

Committee Member

Cui, Xin

Committee Member

Wipf, David O.

Committee Member

Montiel Palma, Virginia

Committee Member

Creutz, Sidney

Date of Degree

5-10-2024

Document Type

Dissertation - Open Access

Major

Chemistry

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Arts and Sciences

Department

Department of Chemistry

Abstract

The industrial revolution came with its downside of emission of greenhouse gases into the atmosphere. The NOAA reported in 2019 that, of the greenhouse gases emitted into the atmosphere, CO2 contributed to about 80% of the increased greenhouse gases hence the need for CO2 Sequestering and Storage (CSS) and ultimately leading to Carbon Capture and Recycling (CCR) as a viable option to convert CO2 into useful forms. The race to find the best catalyst for CCR has led to the synthesis of many organometallic compounds. Pincer complexes catalyzed CO2 reduction has gained notoriety recently because of the tunability and robustness without causing any alteration in their overall coordination geometry. Different metals and pincer motifs have been reported for the electrocatalytic and photochemical reduction of CO2. Chapter I introduces the broader project impact, N-heterocyclic carbene concepts, pincer chemistry, iron pincer chemistry, and N-heterocyclic pincer complexes of Fe for a comprehensive perspective. Chapter II addresses the scarcity of iron based NHC pincer complexes due to deprotonation challenges and octahedral coordination preferences. Bulky substituents like mesityl, adamantly, or DIPP enable mono-ligated pincer complexes by hindering ligand encapsulation, leaving no open coordination site. In-situ metalation / transmetalation, and isolated CCC-NHC Zr complexes are presented along with a method to convert between mono-ligated and bis-ligated complexes. Chapter III explores L-type ligands' reactivity to prevent ligand reorganization around the Fe center from Chapter I. Chapter IV covers CCC-NHC Fe pincer complexes' synthesis, characterization, and transient absorption studies of bis-ligated complexes. Characterization of the CCC-NHC pincer Fe complexes in Chapter I-IV were carried out using 1H and 13C NMR spectroscopy, ESI-TOF MS, EA (Elemental Analysis), cyclic voltammetry, and X-ray diffraction. Chapter V discusses catalytic experiments and data consistent with preliminary CO2 reduction with mono-ligated CCC-NHC pincer complexes.

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