Physical Sciences and Mathematics Commons^™

The Chemistry And Catalytic Activity Of Dehydrogenative Silylation And Hydroboration Of Complexes Bearing Semirigid Ligands With Group 14 Elements, Niroshani S. Abeynayake

Theses and Dissertations

Incorporation of silicon in the ligand backbone would yield electron-rich metal complexes upon coordination to transition metal complexes. The coordination chemistry of semirigid benzyl phosphines bearing a single or multiple phosphorus atoms and varying number of Si−H moieties has gained interest in recent years. This dissertation focuses on synthesizing silyl and germyl transition metal complexes of groups 9 and 10. Chapter II presents the synthesis of a family of four coordinated 14-electron rhodium complexes. The newly synthesized complexes were characterized in solution by multinuclear NMR spectroscopy and in the solid-state by single-crystal X-ray diffraction. These d⁶ complexes possess sawhorse …

Synthesis And Study Of Unsymmetrical Bidentate Bis(Phosphino)Pyrrole Ligands And Their Transition Metal Complexes, Julia F. Vidlak

Honors Theses

Our laboratory has reported the synthesis and characterization of a broad library of unsymmetrical bidentate bis(phosphino)pyrrole (BPP) ancillary ligands for use in nickel-catalyzed cross-coupling reactions. The electronic and steric properties of nickel complexes bearing these ligands are examined, and our data support the hypothesis that these ligands produce nickel complexes with electron-deficient metal centers. The syntheses of (BPP)Ni(o-tolyl)Cl precatalysts for utilization in nickel-catalyzed Buchwald-Hartwig Amination are described, and preliminary reactivity studies reveal that (BPP)Ni(o-tolyl)Cl precatalysts are effective in promoting C–N cross-coupling reactions. Finally, we report steric measurements and electronic properties obtained from computed (BPP)NiCl2 and (BPP)Ni(CO)2 complexes, respectively. Additional reactivity …

Dirhenium Compounds Containing The Diphosphine Ligands Ph2pch2pph2, Ph2pch(Cn)Pph2, Or Ph2pch(Ch3)Pph2: A Comparative Study, Hannah C. Arthur

Undergraduate Honors Theses

When M₂L₁₀ complexes containing two rhenium(III) atoms in a quadruple bond react with an excess of the diphosphine ligand Ph₂PCH₂PPh₂, the bond order decreases, and the rhenium is reduced to rhenium(II). When two diphosphine ligands are bonded to the dirhenium center, they can adopt a trans-trans, trans-cis, or cis-cis configuration. NMR spectra of compounds that adopt the cis-cis arrangement show unusually large downfield shifts for one of the bridgehead methylene hydrogens (P-CH₂-P). To understand the unusual chemical shift, the hydrogens first have to be assigned. The strategy for …

Synthesis, Study, And Applications Of Highly Fluorinated Copper Pyrazolate Complexes Of Small Alkene, Alkynes And Carbon Monoxide, Devaborniny Parasar

Chemistry & Biochemistry Dissertations

Trinuclear copper pyrazolate complexes (copper trimers) function as excellent precursors to synthesize multinuclear complexes of copper. Using highly fluorinated pyrazolates as supporting ligands, we have successfully synthesized and isolated several unique complexes of copper with alkene (e.g., ethylene), alkynes (e.g., 3-hexyne, butyne, acetylene, etc.) and carbon monoxide from the copper trimers. Synthetic details, solid-state structures, and physico-chemical properties of a series of multinuclear complexes have been studied. Chapter 2 of this research work focuses on the olefin/paraffin separation technology. For this we have succesfully synthesized a novel, highly fluorinated copper pyrazolate complex, that undergoes remarkable structural rearrangement forming a dinuclear …

Mechanistic Study Of Cooperative Ligand-Centered Reactivity In Triaminoborane-Bridged Diphosphine Complexes, Clara Kirkvold

Honors Thesis

Reactive ligand platforms containing trisubstituted boranes have been effective in promoting new types of small molecule reactivity and catalysis with transition metals. Our project is aimed at developing triaminoborane-bridged diphosphines that participate in cooperative ligand-centered reactivity while bound to transitions metals. Here we present a density functional theory (DFT) mechanistic study on a series of ligand centered reactions at a boron center on a metal complex, ^PhTBDPhosMCl₂ (M = Ni or Pd and TBDPhos = 1,8,10,9-triazaboradecalin). Our work focuses specifically on the nickel complexes. ^PhTBDPhosNiCl₂ can react with several molecules to produce trans H-X addition (X=OH …

Zinc Proteomics: Interactions Of Zn2+, Cd2+, And Metal-Binding Ligands With Zn-Binding Sites In The Proteome, Eric Daniel Lund

Theses and Dissertations

Cadmium ion causes toxicity in humans, most prominently in the kidney. This thesis focuses on mechanisms by which Cd2+ harms kidney proximal tubule cells. Previous experiments have shown the time-dependent distribution of Cd2+ and Zn2+ within supernatant of pig kidney, LLC-PK1 cells after exposure to Cd2+ plus the ionophore pyrithione1. The first part of this research describes the trafficking of cadmium within LLC-PK1 proximal tubule cells, including the time dependent distribution, speciation, and quantification of Cd2+ and Zn2+ in cells exposed to Cd2+ and Cd2+ plus pyrithione. The latter treatment introduces Cd2+ into cells at time zero and permits the …

Preparation Of Organometallic Cobalt(Iii) Complexes Containing Bidentate Chiral Amine Ligands As Potential Transfer Hydrogenation Catalysts, Luccas C. Do Carmo

Honors Theses

Mixed coordination sphere cobalt(III) complexes containing a chiral bidentate amine ligand and an organic carbocyclic ligand have been prepared and characterized. The integration of this mixed ligand environment involving an organometallic and Werner-type ligand along with the earth abundant metal in a high oxidation state has the potential for interesting reactivity. Complexes of the type [Co(CpR)(X-DPEN)(I)](I), where CpR = cyclopentadienyl (Cp, R = H) or pentamethylcyclopentadienyl (Cp*, R = Me) and X = meso-1,2-, 1R,2R-, and 1S,2S-, have been prepared by ligand substitution from [Co(CpR)(I)2(CO)] with 1,2-diphenyletheylenediamine (DPEN). The outer sphere iodide is readily exchangeable with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF) or …

Synthesis, Characterization And Mechanistic Studies Of Biomimetic Dinuclear Copper(Ii) Complexes, Millaniyage Nuwanthaka Prasad Jayaweera

Masters Theses

Dinuclear copper complexes are significant synthetic targets due to their use as model compounds for the active sites of type 3 copper proteins like catechol oxidase. A distinct class of ligands used in these studies are built on a phenol core to witch various donor side-arms were appended at the 2 and 6 positions of the arene ring. In our quest to quantify the influence of electron donating or withdrawing groups attached to the central arene ring, we have designed a set of ligands that, upon coordination to copper(II) centers, would produce complexes of the general structure. During this research …

Synthesis Of New Bodipy Analogs, John Dilyard

Williams Honors College, Honors Research Projects

This report examines the synthesis of new ligands based upon dipyrazolylmethane and diindazolylmethane. The goal of these modifications is to increase the acidity of the proton on the methyl carbon to allow for deprotonation. The ligands synthesized were dipyrazolylphenylmethane and diindazolylphenylmethane, as well as modifications of the latter. The products were analyzed by NMR spectroscopy and one crystal structure was obtained of diindazolylphenylmethane.

Chemical Reduction Of Polycyclic Aromatic Ligands With Heavy Group 2 Metals, Andrew Robert Uresk

Legacy Theses & Dissertations (2009 - 2024)

The chemistry of the alkaline earth metals has received a renewed interest in the last decades. The lighter Group 2 metal, magnesium, has gathered the most attention, as it is a key component of Grignard reagents, while the heavier metals have been less studied. The early alkaline earth metals are known to exhibit some similarity with both the alkali and lanthanide metals in π-complexation reactions with planar aromatic hydrocarbons (PAHs). However, the products of heavier Group 2 elements such as strontium and barium were found to be more difficult to synthesize and isolate, thus requiring the development of new synthetic …

Homo- And Heterometallic Bis(Pentafluorobenzoyl)Methanide Complexes Of Copper(Ii) And Cobalt(Ii), Janell Crowder

Legacy Theses & Dissertations (2009 - 2024)

β-Diketones are well known to form metal complexes with practically every known metal and metalloid. Metal complexes of fluorinated β-diketones generally exhibit increased volatility and thermal stability compared to the non-fluorinated analogues, and thus are used extensively in various chemical vapor deposition (CVD) processes for the deposition of metal, simple or mixed metal oxides, and fluorine-doped metal oxide thin films. Furthermore, the electron-withdrawing nature of the fluorinated ligand enhances the Lewis acidity of a coordinatively unsaturated metal center which facilitates additional coordination reactions. The physical and structural properties of fluorinated β-diketonate complexes are discussed in Chapter 1 …

Synthesis And Utility Of Bis-Urea Macrocycles As Nanoreactors And As Ligands For Metal Organic Materials, Sahan R. Salpage

Theses and Dissertations

“Supramolecular chemistry” powered by non-covalent interactive forces forms the crux in the area of host-guest chemistry. Supramolecular assemblies often have different chemical and physical properties than that of its individual molecular entities and are used to develop novel functional materials. Our expertise involves making functional materials from macrocycles, which contain two urea groups and two rigid C shaped spacer groups. These individual macrocyclic components can self-assemble through hydrogen bonding and other non-covalent interactions to form porous supramolecular assemblies that can be used as confined reaction environments and as ligands to synthesize novel metal organic materials.

This dissertation focuses on studying …

Mixed Ligand Approach To Design Heterometallic Single-Source Precursors For Low-Temperature Preparation Of Oxide Materials, Craig Matthew Lieberman

Legacy Theses & Dissertations (2009 - 2024)

There is a considerable interest in the use of metal oxides for development of novel high-technological materials such as gas sensors, multiferroics, and electrocatalysts. In particular, the design of complex oxides, which incorporate more than one type of metal atom, is focused on enriching chemical and physical properties of the target materials and allowing for increased functionality. In order to replace the harsh conditions associated with traditional synthetic routes that often require high temperatures and/or pressures, new soft chemistry methods for the preparation of mixed-metal oxide materials have been developed. One of the most promising directions is the emergence of …

Syntheses And Structures Of Iron(Ii) And Cobalt(Ii) Complexes Of Substituted Tetra(Pyrazolyl)Lutidine Derivatives, Heidi Marie Tatlock

Master's Theses (2009 -)

Pentadentate ligands provide stability to metal complexes as well as a binding site for substrates that make them exceptionally useful for studying reactions. They have been used in biomimetic studies, water splitting, and small molecule activation studies. A series of six pentadentate ligands derived from a,a,a',a'-tetra(pyrazolyl)lutidine, pz4lut, with methyl substituents decorating the ligand periphery has been synthesized. These ligands were coordinated to FeIICl, and the electronic and structural properties of the resulting complexes were studied in order to deduce the effects of methyl substitution at the 3-, 4-, and 5-positions of the pyrazolyl groups and at the methine positions. When …

Novel Resist Systems For Euv Lithography : Ler, Chain-Scission, Nanoparticle And More, Brian Cardineau

Legacy Theses & Dissertations (2009 - 2024)

Extreme Ultraviolet (EUV) lithography is currently the best option for replacing 193-nm lithography in future IC fabrication. For EUV to be successful, however, there are a number of challenges that must be overcome. Current resist designs struggle to meet the demands of future lithography nodes. We propose the best way to overcome these obstacles is through the design of novel resist systems.

Part I - A Study Of The Formation Of Carbenes By Elimination Of Α-Bromosilanes And Application Toward The Synthesis Of Transition Metal Complexed Quinone Methide Analogs. Part Ii - Development Of Novel 7-Membered Ring Carbene Ligands For Palladium Catalyzed Cross Coupling Reactions., Christian Michael Loeschel

Graduate Theses and Dissertations

In part I, we wish to report our approaches toward transition metal complexed ortho-quinone methide analogs. ortho-Quinone Methides are a class of highly reactive compounds with a wide range of chemical and biological applications. Previously, a stable iron complexed benzannulated 5-membered ring quinone methide analog was reported by Allison and Neal27. Herein, we report our approaches to improve the reactivity of that system by removing benzannulation as well as changing the metal from iron to manganese and rhenium.

Furthermore, a methodological study on generating carbenes under mild conditions by elimination of α-halosilanes and its application towards metal complexed quinone methide …

The Impact Of Ligand Design On The Coordination Chemistry And Reactivity Of Metal Pincer Complexes, Sarath Wanniarachchi

Dissertations (1934 -)

Pincer ligands are uninegative tridentate metal-coordinating agents of the form [XZY]- where Z is the central, anchoring Lewis donor while X and Y are flanking Lewis donors. Ever since initial reports of transition metal pincer complexes were published in the late 1970's, there has been burgeoning interest in such complexes because of their desirable robust nature, generally simple syntheses, and the spectacular chemical transformations that they can mediate. In this research project, two new sets of pincer ligands with a diarylamido anchor and either two pyrazolyl nitrogenous flanking donors (NNN pincer) or one pyrazolyl and one diphenylphosphine donor (NNP pincer) …

Nmr-Based And Automated Docking Characterization Of Protein Structure, Dynamics, And Ligand Binding, Andrew Lawrence Olson

Dissertations (1934 -)

NMR-based methods used in conjunction with a technique called docking are used to characterize ligand binding to proteins. Standard NMR methods were used to study the backbone dynamics of substrate binding to phosphomevalonate kinase (PMK) and it was observed that ligand binding caused PMK to undergo large conformational changes. These changes were reflected by the appearance of many chemical shift changes upon binding of the natural substrates of PMK (both the binary and ternary complexes) in 1H-15N HSQC NMR titration experiments. The same process was used to characterize the effect ligand binding has on the many arginines in the active …

Cyanoscorpionates And Transition Metal Complexes., Donald Martin Johnson

Electronic Theses and Dissertations

The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.

Coordination Chemistry Of Tetra(Pyrazolyl)-Lutidine Ligands And Derivatives, Tyler James Morin

Dissertations (1934 -)

There is current interest in the coordination chemistry of simple AE4 pentadentate ligands that occupy one axial (A) and four equatorial (E) positions about a given transition metal center considering that systems capable of mediating spectacular organic transformations such as alkane oxidation have been identified. The discovery of new systems will improve understanding of C-H bond activation processes which is critical to help make more efficient use of the currently diminishing fossil fuel supplies. As such, a new pentadentate ligand α,α,α',α'-tetra(pyrazolyl)lutidine (pz4lut) and its derivatives pz4,4lut, (pz4, = 4-methylpyrazole); pz*4lut, (pz* = 3,5-dimethylpyrazole); pzDIP4lut, (pzDIP = 3,5-diisopropylpyrazole) have been synthesized …

Investigation Of Iron (Iii) Desferrioxamine B Oxalate Ligand Exchange By Uv-Vis Spectroscopy: The Next Step In Developing A Quantitative Analytical Method For Measuring Bioavailable Iron In Marine Ecosystems, Ken L. Pitter

Honors Theses

To date there are no analytical techniques designed to exclusively measure bioavailable iron in marine environments. The goal of this research is to develop such a technique by isolating the bioavailable iron using the terrestrial siderophore desferrioxamine B (DFB). This project contained many challenging aspects, but the specific goal of this study was to develop a robust analytical technique for quantification of Fe(III)-DFB complexes at nanomolar concentrations. Past work showed that oxalate (Ox) promotes photodissociation of Fe(III)-DFB to Fe(Il), and we are specifically interested in the mechanism of this process. A model was developed using known thermodynamic constants for Fe(III)-DFB …

Probing The Capabilities Of Copper Complexes With Nitrogen And Sulfur Containing Macrocyclic Ligands As Aziridination Catalysts, Jonathan Natkin

Honors Theses

Aziridines are three-membered rings containing one nitrogen atom. They are useful as synthetic intermediates in many organic reactions. Much work has been devoted to synthesizing their analogs, cyclopropanes and epoxides, but little work has been done on the aziridination reaction. This study endeavored to probe the efficiencies of novel copper aziridination catalysts with N3 and S3 macrocyclic ligands compared to an NS2 analog for the reaction with the nitrene precursor (N-(paratosylsulfonyl) imino)phenyliodinane, PhINTs, and the olefin styrene. The nitrogen containing catalyst complex gave higher yields than the sulfur containing catalyst complex. Both ligands were found to decrease the yield of …

Ion Selective Electrodes Based On Aza- Substituted Crown Ethers, Lisa Ann Wellington

Retrospective Theses and Dissertations

A cation-responsive electrode system has been developed which incorporates aza-substituted crown ethers as ligands. In a novel application, uncomplexed crown ethers were used in the pelletized form for ionic transport. Electrodes have been produced which can be conditioned for a particular ion and following their use, be reconditioned and reused for other ions. Preparation method and lifetime studies are included.

The responses of two crown ethers with plasticizers were evaluated for thirteen representative cations. The concentration range covered in each evaluation was 1 x 10^-1 to 1 x 10^-7 M. For those ions exhibiting Nernstian or near-Nernstian response, …

New Evidence Supporting The Assignment Of Glutamic Acid As An Iron Ligand In Hemerythrin, Patricia M. Gormley

Dissertations and Theses

The amino acid sequence determination of Phascolopsis gouldii hemerythrin in the region of the proposed iron ligand at position 58 was the main objective of this research endeavor. Generation of a large peptide was pursued by trypsin digestion of citraconylated hemerythrin producing peptide 50-113 for sequenator analysis. Detection of the phenylthiohydantoin amino acid derivatives by gas-liquid and high-performance-liquid chromatography yielded unambiguous sequence elucidation through the region of interest identifying residue 58 as glutamic acid.

The Synthesis Of 2-Carboxyethyl-P, P-Diphenylphosphine And A Study Of It As A Potential Chelating Agent, Harriet V. Taylor

Chemistry Honors Papers

This 24 page thesis examines the synthesis of organo-phosphorous acids and their stability as ligands.