Inorganic Chemistry Commons^™

Ambient Ammonia Synthesis Via Microwave-Catalytic Materials And Plasma Chemistry, Siobhan Brown

Graduate Theses, Dissertations, and Problem Reports

Ammonia is critical to supporting human life on earth because of its use as fertilizer. The Haber-Bosch process to produce ammonia has been practiced for over 100 years. This process operates at high pressure and temperature to overcome the thermodynamic and kinetic limitations of the ammonia synthesis reaction thus researchers have tried to overcome it for decades. At present this process represents 1% of global energy usage and 2.5% of global CO₂ emissions. The proposed chemical looping ammonia synthesis approach seeks to reduce the environmental impact of this critical process and to elucidate microwave-catalytic principles.

This research aims to …

Exploration Of Metal-Carbonyl Complexes For Decarbonylation Reactions, Rebekah C. Krupa

Graduate Theses, Dissertations, and Problem Reports

In recent years, transition metal-mediated decarbonylation reactions have emerged as an alternative to conventional cross-coupling methods due to the advantages associated with the use of carbonyl-containing functionalities as coupling electrophiles instead of organohalides found in traditional cross-coupling reactions. This, coupled with the ubiquity of carbonyl-containing compounds in pharmaceuticals and non-biodegradable chemicals, has led to the interest in developing efficient systems for transition metal-catalyzed decarbonylation. However, these reactions are commonly limited to stoichiometric amounts of metal reagents due to the strong metal-carbonyl bond formed during transition metal-mediated decarbonylation. With the goal of gaining a better mechanistic understanding of CO dissociation in …

Electronic Structure Of Early Transition Metal Complexes Supported By Pyridine Polypyrrolide Ligands, Dylan Connor Leary

Graduate Theses, Dissertations, and Problem Reports

A thorough study of photoluminescent molecules involving the pyridine polypyrrole(ide) ligand platform has been conducted. A detailed analysis on speciation of the proligand H₂(^MesPDP^Ph) (H₂^MesPDP^Ph = 2,6-bis(5-mesityl-3-phenyl-1H-pyrrol-2-yl)-pyridine) and its dilithium salt Li₂(^MesPDP^Ph) revealed temperature- and solvent-dependent effects. These molecules, along with the hydrochloric acid adduct [H₃(^MesPDP^Ph)]Cl were found to exhibit short-lived photoluminescence in both tetrahydrofuran and benzene solution. These findings confirm the hypothesis that heavy-atom involvement is crucial for the favorable photophysical properties observed for the Zr(PDP)_{2 …}

Synthesis, Characterization, And Activation Of Pyridine Dipyrrolide Supported Vanadium-Nitrogen Multiple Bonds, Jordan Cruz Martinez

Graduate Theses, Dissertations, and Problem Reports

The chemistry of coordination complexes of vanadium supported by pyridine di-pyrrolide pincer ligands was probed via the synthesis and investigation of a variety of compounds from the trivalent starting material, (^MesPDP^Ph)VCl(thf)₂. Under reducing conditions and subsequent addition of terpyridine, a redox transfer series (1-, 0, 1+) stemming from the neutral product (^MesPDP^Ph)V(terpy) was isolated and characterized by X-ray crystallography. The precise bond lengths, in conjunction with bulk magnetic susceptibility, allowed for a detailed study of the redox non-innocence of polypyridyl ligands in these systems.

Metathesis of the halide starting material …

Modeling, Fabrication, And Characterization Of Rf-Based Passive Wireless Sensors Composed Of Refractory Semiconducting Ceramics For High Temperature Applications, Kavin Sivaneri Varadharajan Idhaiam

Graduate Theses, Dissertations, and Problem Reports

Real-time health monitoring of high temperature systems (>500^oC) in harsh environments is necessary to prevent catastrophic events caused by structural failures, varying pressure, and chemical reactions. Conventional solid-state temperature sensors such as resistance temperature detectors (RTDs) and thermocouples are restricted by their operating environments, sensor dimensions and often require external power sources for their operation. The current work presents the research and development of RF-based passive wireless sensing technology targeting high temperatures and harsh environmental conditions. Passive wireless devices are generally classified as near-field and far-field devices based on the interrogation distance. Near-field sensors are placed at …

Characterization Of Modern Ammunition And Background Profiles: A Novel Approach And Probabilistic Interpretation Of Inorganic Gunshot Residue, Korina Layli Menking-Hoggatt

Graduate Theses, Dissertations, and Problem Reports

Gunshot residue (GSR) can provide essential clues in gun-related investigations. The standard practice for GSR analysis uses SEM-EDS, with the capability for single particle elemental and morphological analysis. However, the method is time-consuming and based on categorical classification models without considering case circumstances. Therefore, complementary and more encompassing methods are needed to improve evidence interpretation of modern ammunition. This research aims to fill these demands by developing standard materials and alternative methods to characterize and interpret IGSR.

This study developed primer GSR (pGSR) standards from sixty discharged primers that were fully characterized by three techniques. The number of GSR particles, …

Cobalt-Catalyzed Aerobic Oxidative Cyclization Reactions Of Bisnucleophiles: New Methodologies And The Role Of Bisnucleophiles In O2 Activation, Jiaqi Liu

Graduate Theses, Dissertations, and Problem Reports

Over the past few decades, transition metals have found wide applications in the development of selective oxidative transformations mediated by molecular oxygen. Due to the benign nature of molecular oxygen as an oxidant and an increasing awareness of green chemistry practice, tremendous progress has been made towards the development of Cu-and Pd-catalyzed aerobic oxidation reactions. As a first-row transition metal alternative to copper, cobalt has been employed in aerobic catalytic transformations for its cost-efficiency and earth abundance; however, redox-active mediators such as benzoquinone (BQ), N-hydroxyphthalimide (NHPI) or salen-type ligands are usually required. To date, reactions mediated by Co/O₂ catalytic …

Synthesis And Characterization Of Pyridine Dipyrrolide Iron Complexes Relevant To Nitrene And Carbene Group Transfer, Brett M. Hakey

Graduate Theses, Dissertations, and Problem Reports

The synthesis and electronic structures of the square-planar high-spin Fe^II complexes (^MesPDP^Ph)Fe(OEt₂) and (^MesPDP^Ph)Fe(thf) were investigated. Analysis of these compounds using a combination of ¹H NMR and ⁵⁷Fe Mössbauer spectroscopies, in conjunction with computational analysis, has resulted in a rationalization for their unusual electronic structures, which arise from the unique coordination environment enforced by the pyridine dipyrrolide chelate ligand.

The reactivity of (^MesPDP^Ph)Fe(thf) with organic azides has been probed and resulted in the isolation of an array of products that are consistent with …

Mechanistic Analysis Of Reductive Boracarboxylation Using Low Valent Copper And Co2, Notashia Nicole Baughman

Graduate Theses, Dissertations, and Problem Reports

The synthesis of organoboron compounds is of contemporary importance in the chemistry community given their utility in subsequent functionalization reactions as well as their growing therapeutic potential in the treatment of human disease. This, coupled with the ubiquity of carboxylic acid functional groups in pharmaceuticals and fine chemicals, has led to interest in one-pot difunctionalization reactions using CO₂ and a boron source. An (ICy)copper(I)-catalyzed boracarboxylation reaction was recently developed wherein CO₂ and a pinacolboryl group is added across the double bond of vinyl arenes was recently developed, providing access to α-aryl-β-boryl propionic acid derivatives. A subsequent publication detailed …

Photoluminescent Zirconium Complexes For Visible Light Photoredox Catalysis, Yu Zhang

Graduate Theses, Dissertations, and Problem Reports

Early transition metals like zirconium are attractive candidates for the design of luminescent molecules based on earth-abundant elements. Here, a series of zirconium complexes carrying two pyrrolyl-based ligands have been synthesized and characterized. These complexes are photoluminescent upon excitation with visible light and exhibit remarkably long emission lifetimes of hundreds of μs in solution at room temperature. Computational studies using time-dependent density functional theory (TD-DFT) were conducted to identify the nature of the luminescent excited states as mixed intra-ligand/ligand-to-metal charge-transfer (ILCT/LMCT) states. The electrochemistry studies revealed multiple reversible redox events for each zirconium complex. Furthermore, the excited state of the …

In Situ Infrared Spectroscopic Study Of Iron-Catalyzed Hydromagnesiation Of Vinyl Arenes, Jessica Ann Rogers

Graduate Theses, Dissertations, and Problem Reports

Iron catalysis, especially homogeneous catalysis, has been a resurging topic of organometallic chemistry research. Discussions of past and present mechanistic analyses for homogeneous iron catalysis will be discussed in Chapter 1. As an expansion of homogeneous iron catalysis, in situ infrared spectroscopy will be used to develop a full mechanistic study of iron-catalyzed hydromagnesiation of vinyl arenes. The kinetic analyses by both initial and observed rate measurements indicate complex concentration dependencies on the (PDI)iron catalyst as well as sacrificial Grignard reagent and styrene. These complexities are not limited to non-linear catalyst and Grignard initial rate and inhibition by styrene/Grignard at …

Nickel-Catalyzed Oxidative Decarboxylative (Hetero)Arylation Reactions, Aaron P. Honeycutt

Graduate Theses, Dissertations, and Problem Reports

Transition-metal-catalyzed decarboxylative coupling reactions have gained considerable attention over the past decade as an efficient route to form heterobiaryls. However, current methods for oxidative decarboxylative (hetero)arylation with unactivated C-H bonds have been limited by poor substrate scope, control of regioselectivity, and chemospecificity. This thesis describes the development of a new nickel-catalyzed oxidative decarboxylative coupling (ODC) with unactivated C-H bonds. The first chapter discusses the development of the new nickel-catalyzed ODC reaction to enable the coupling of a N,N'-bidentate directing group with a broad scope of heteroaromatic carboxylates and ortho-substituted benzoates, a scope that has not been achieved in previous …