Inorganic Chemistry Commons^™

Magnetic Properties And Biological Relevance Of Scorpionate-Based Transition Metal Complexes, Laxmi Devkota

Dissertations (1934 -)

There are two major components to this research dissertation. The first component describes the synthesis and characterization of high-spin, first-row transition metal complexes supported by facially-coordinating “scorpionate” ligands. These studies have sought to uncover fundamental relationships between molecular structure and magnetic properties, with the ultimate aim of assisting in the design of single molecule magnets (SMMs). To this end, comprehensive series of four and five-coordinated M(II)-X complexes (M = Co, Fe, and Cu; and X = F, Cl, Br, and I) were prepared using hydrotris(pyrazol-1-yl)borate ligands (TpR,R’; where R and R’ indicate substituents at the 3- and 5-position of the …

Spin Crossover Behavior Of N-Confused C-Scorpionate Complexes Of Iron(Ii) Trifluoromethanesulfonate, Kristin Joy Meise

Master's Theses (2009 -)

An understanding of the molecular properties that influence highly-cooperative SCO behavior is critical in the development of new electronic materials. The purpose of this thesis work is to more fully examine whether hydrogen bonding interactions can be used to assemble iron(II) scorpionate complexes and whether this leads to abruptness in the SCO behavior. In this contribution, new N-confused C-scorpionate ligands are prepared with two ‘normal’ pz* groups ( = 3,5-dimethylpyrazol-1yl) and a ‘confused’ pyrazolyl with either an N-H, HL*, or an N-Tosyl (Tosyl = p-toluenesulfonyl), TsL*, bound to a central methine. These bulky ligands complement those previously described, HL and …

Ruthenium Catalyzed Deaminative Coupling Reaction Of Amines Via C-N Bond Activation, Pandula T. Kirinde Arachchige

Master's Theses (2009 -)

C–N bond activation via transition-metal catalyst has attracted much attention during the past two decades. This strategy has become one of the most promising way to generate secondary amines, which are very important in a broad spectrum of applications in pharmaceutical industry, synthetic organic chemistry and material science. The secondary amines can be utilized as an important synthetic intermediate for further manipulations. The in-situ formed catalytic system generated from the tetranuclear Ru–H complex with 4-(1,1-dimethylethyl)-1,2-benzenediol ligand was found to be effective for the synthesis of secondary amines from the direct deaminative coupling of amines. The ruthenium catalyst was highly effective …

Ruthenium-Catalyzed Dehydrogenative And Dehydrative C-H Coupling Reactions Of Arenes With Alcohols And Carbonyl Compounds, Hanbin Lee

Dissertations (1934 -)

Despite their outstanding achievements, the requirement of preformed functional groups and wasteful byproduct formation are inherent disadvantages associated with the transition metal catalyzed cross-coupling methods. Inspired by the needs for green and sustainable chemistry, transition metal catalyzed dehydrogenative and dehydrative coupling methods have been recognized as environmentally sustainable and atom economical synthetic routes for the new C-C bond formation. The catalytic activation of C-H and C-O bonds allows the formation of coupling products from ubiquitous hydrocarbon substrates by releasing hydrogen or water byproduct. However, these novel protocols require relatively harsh conditions due to their low reactivity of C-H and C-O …

Development Of New Ligand Scaffolds For The Preparation Of Heterobimetallic Complexes, Alexander Richard Treleven

Master's Theses (2009 -)

There is currently much interest in the development of methods to harness sustainable, CO2 neutral, non-fossil fuel based energy sources due to diminishing worldwide supply of fossil fuels and concerns over historically high levels of CO2 in the atmosphere, which may have a devastating impact on the world’s climate. One such avenue is through the conversion of atmospheric CO2 into useful, high-energy density, organic fuel sources. Photosynthesis is the biological process by which plants convert sunlight, water, and CO2 into the reduced organic materials that we extract from the earth and burn (completing the cycle back to CO2) to release …

Synthesis And Characterization Of Biologically Relevant Fe(Ii) Complexes Containing Redox-Active (Hydro)Quinone Ligands, Amanda Elizabeth Baum

Dissertations (1934 -)

Redox-active p-(hydro)quinones work in concert with transition-metal centers to facilitate electron transfers in numerous biological contexts. While p-(hydro)quinones are known to interact with both heme and nonheme iron cofactors, the nonheme systems are particularly relevant to photosynthetic and bioremediation processes. In photosynthesis, two p-quinones facilitate an electron transfer away from the photoexcited P680 cofactor via a non-heme Fe(II) center. Based on EPR results, this interaction results in formation of transient Fe(II)/p-semiquinone (pSQ) species. In addition, a superoxo-iron(II)-pSQ species has been proposed as an intermediate of the oxidative cleavage mechanism of hydroquinone dioxygenases (HQDOs), which play a central role in the …

Ligand Frameworks For Transition-Metal Complexes That Model Metalloenzyme Active, Denan Wang

Dissertations (1934 -)

Advances in the field of biomimetic inorganic chemistry require the design of sophisticated ligand frameworks that reflect the amazing complexity of metalloenzyme active sites. For instance, most active sites feature extensive hydrogen-bonding interactions between ligands bound to the metal center (the “first” coordination sphere) and nearby units in the outer (or “second”) sphere. Since these interactions modify the structural and electronic properties of the active sites, a number of inorganic chemists have sought to design ligands that permit outer-sphere functional groups to interact with first-sphere donors. This dissertation describes our contribution to these broader efforts to model the second coordination …

Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C, C-N And C-O Bond Activation Reactions, Nishantha Kumara Kalutharage

Dissertations (1934 -)

Transition metal catalyzed selective C-C, C-N and C-O bond activation reactions are fundamentally important in organometallic chemistry and organic synthesis. Catalytic C-C, C-N and C-O activation are highly valuable for reforming processes of crude oils. Significant research has been devoted to transition metal mediated C-C, C-N and C-O bond cleavage reactions to form new compounds as these processes are expected to provide novel ways to transformation of inexpensive hydrocarbons into more commercially valuable products such as pharmaceuticals, agrochemicals and polymers. A few examples of transition metal catalyzed cross coupling reactions involving C-N bond cleavage have been reported. A well-defined Ru …

Synthesis, Characterization And Reactivity Studies Of Fe(Ii) Complexes With Relevance To The Radical Sam Enzymes, Xixi Hong

Master's Theses (2009 -)

It is well-established that S-adenosylmethionine (SAM) serves as the methyl group donor in methylations of DNA, hormones, neurotransmitters and signal transduction systems. However, a new class of enzymatic reactions involving SAM has recently attracted considerable attention. In these systems, SAM initiates radical-based reactions at the active sites of enzymes via formation of an adenosyl radical, which further abstracts a H-atom from the substrate to initiate a radical-based mechanism. However, modeling studies of radical SAM enzymes have been hindered, by difficulties in preparing adequate synthetic [Fe4S4] clusters. We prepared a novel series of Fe(II) complexes with tripodal tris(2-hydroxybenzyl)amine ligands, which replicate …

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) …

Synthesis And Characterization Of Iron(Ii) Complexes Modeling The Active Site Structure Of Nonheme Iron Dioxygenases, Jacob Baus

Master's Theses (2009 -)

The aerobic degradation of polycyclic aromatic compounds, which are widespread contaminants in soils and groundwaters, is carried-out in large part by various Fe-containing dioxygenases that perform the cis-dihydroxylation and oxidative cleavage of aromatic rings. Recently, a new Fe dioxygenase family emerged that catalyzes a remarkable set of transformations; the distinguishing feature of these enzymes is that their monoiron(II) centers are coordinated by three histidines residues (i.e., imidazole ligands) in a facial geometry - a departure from the "canonical" 2-histidine-1-carboxylate facial triad that is dominant among nonheme monoiron enzymes. Members of the "3His family" are capable of oxidatively cleaving C-C bonds …

Synthetic And Mechanistic Studies Of Coupling Reactions Involving C-H Bond Activation, Ki Hyeok Kwon

Dissertations (1934 -)

Transition metal-catalyzed C-C bond forming reactions involving C-H bond activation have been shown to be effective methods for functionalization of unreactive compounds. Since Murai's pioneering work on ruthenium-catalyzed regioselective arene-to-alkene coupling reactions, a number of well-defined, late transition metal catalysts have been shown to mediate regioseletive C-C bond forming reaction involving C-H bond activation. Recently, late transition metal complexes have also been found to catalyze the regioselective coupling reaction of nitrogen containing compounds with alkenes as well as sp3 bond insertions and oxidative coupling reaction of aimdes. The catalytic C-C bond forming reaction involving C-H bond activation would provide simple …

Synthesis And Reactions Of A Tungsten Dioxo Complex, Deborah Bryant

Master's Theses (2009 -)

Metal dioxo complexes are largely known for their ability to epoxidize olefins. The importance of these reactions is reflected in the patents for the ARCO and Halcon processes from the late 1960's. It is very difficult to find literature that shows other indications for metal dioxo complexes.

Catalytic olefin dimerization has become significant in the realm of green chemistry for "atom economical" reactions. Many transition metals have been examined as catalysts for olefin dimerization, but the largest volume of work has been performed using group 8 transition metals, particularly nickel, palladium and platinum. This is especially true for the specific …

Thermal Degradation Of Acetate-Intercalated Hydroxy Double And Layered Hydroxy Salts, Everson Kandare, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

Two hydroxy double salts (HDSs), zinc copper hydroxy acetate (ZCA) and zinc nickel hydroxy acetate (ZNA), and an analogous layered compound, zinc hydroxy acetate (ZHA), have been prepared by a coprecipitation method. The thermal degradation of these materials was characterized via thermogravimetric analysis (TGA), differential thermal analysis (DTA), and TGA coupled with Fourier transform infrared spectroscopy of gas-phase products, TGA-FTIR. Loss of physisorbed and interlayer H2O was observed between 50 and 150 °C for all compounds. Acetic acid, acetone, water, and CO2 were released at high temperatures with relative acetone yields found to be dependent on precursor identity, with very …

Synthesis And Nuclear Magnetic Resonance Studies Of Some Boron And Nitrogen Substituted Borazines, Michael G. Henk

Master's Theses (1922-2009) Access restricted to Marquette Campus

From the time Stock and Pohland (44) first prepared borazine in 1926 until Schaeffer and Anderson (33) found a convenient method of preparing borazine in 1949, comparatively little work was done with this compound. Since 1949 work with borazine has progressed geometrically. Today there are a large number of borazines known (15, 36). However, fluorine substituted borazines were unknown until 1962 (29) and to this day very little work has been done with fluorine substituted borazines (2, 27, 30). Also, only a few unsymmetrical borazines have been prepared (38, 40, 41, 42). It would be desirable to have a convenient …

The Application Of Qualitative Inorganic Macro Procedures And Reagents To Spot Test Analysis, John Albert Stich

Bachelors’ Theses

Qualitative inorganic analysis is that branch of applied chemistry which has to do with the systematic detection or identification, and separation of the various metals and groups of elements which make up inorganic compounds. The indentification is made on the basis of precipitates and the color changes thereof, which result when a specific reagent is added to a solution of the sample. As opposed to quantitative analysis, measurability is not the essential factor, but it must be possible to observe the reaction easily and indubitably. It is not necessary for the material being tested for to be converted completely to …