The development of a palladium-catalyzed intramolecular carboesterification of unactivated olefins is described. Olefin difunctionalization is a powerful tool for adding complexity to a molecule, and this formal [3+2] cycloaddition generates highly functionalized fused ring systems. Initially discovered by Dr. Yang Li in our group, it was found that when propiolic acids with a pendant terminal olefin were treated with 1 mol % Pd(MeCN)2Cl2, 3 equivalents of copper (II) chloride, and 3 equivalents of lithium chloride in acetonitrile at 50 °C, cyclization occurred in up to 90% yield. The optimization of this reaction and the extension to propiolamides and propargyl alcohols is described in this thesis. A mechanism involving a novel palladium-carboxylate species is proposed. Preliminary investigations into the synthesis of chiral sulfoxide pincer ligands are also described. The nucleophilic aromatic substitution of 1,3-dibromobenzene and 2,6-dichloropyridine with various thiols, followed by oxidation of the sulfides to sulfoxides is investigated as a route to the desired proligands.

The selective manipulation of hydroxyl groups in di- and polyols is a frequently encountered problem in organic synthesis. Such processes are often tedious and/or moderate yielding, and often necessitate multistep protection / deprotection sequences. Applying boron–diol interactions previously exploited in molecular recognition and based on methods previously developed in our research group, we have developed two classes of chemical transformations: 1. Regioselective sulfonylations of carbohydrate derivatives catalyzed by a borinic ester, providing access to the corresponding mono-tosylates in high yields; 2. Selective monoalkylations and monosulfonylations of structurally diverse 1,2- and 1,3-diol substrates.

Since recognizing the significance of reversible oxidative addition of palladium into aryl halides in the synthesis of 2-bromo-indoles, the Lautens group has focused on unusual carbon-halogen reductive eliminations. These efforts led to the discovery of the novel palladium-catalyzed inter- and intramolecular carbohalogenation reaction – the formal addition of an sp2 carbon–iodide bond across an alkene. One current research direction is utilizing a range of aryl halides and pseudohalides as starting materials for carbohalogenation chemistry. This thesis describes complementary research, focusing on the expansion of functional group scope. Carbohalogenation has been developed to synthesize novel products including heteroaromatic compounds and 7-membered rings. Polyunsaturated aryl iodide substrates were investigated with the goal of performing domino carbohalogenation. Ultimately, the successful halogen exchange process was combined with domino carbohalogenation in an efficient halogen-exchange domino reaction. Additionally, preliminary studies on enantioselective carbohalogenation, and functionalization of the neopentyl iodide products are also discussed.

This work began with the synthesis and full characterization of a novel £^-diimine ligand, (2,6-iPr2C6H3N=CH)2C6H4, from the reaction of o-phthaladehyde and the bulky aniline, 2,6-diisopropylaniline. It was observed that any <i>di-ortho</i>-substituted aniline with less bulky groups than isopropyl groups resulted in formation of the corresponding iminisoindolines. Reaction of the £^-diimine ligand with PdCl2 did not result in a seven-membered coordination complex, but in non-palladacyclic complex, [(g-diimine)PdCl(Ý-Cl)]2. Whereas reaction with Pd(OAc)2 gave an S-shaped five-membered trinuclear palladacyclic complex, {1,2-(2,6-iPr2-C6H3N=CH)2-C6H3]Pd(Ý-OAc)2}2Pd. These complexes were found to be active precatalysts for Heck and Suzuki coupling reaction giving TONs of up to 104 and 86, for arylbromides and arylchlorides, respectively.<p> On the other hand, a series of neutral and cationic seven-membered aluminum coordination complexes were obtained from the reaction of £^-diimine with a variety of aluminum species (AlMe3, AlMe2Cl, AlMeCl2 and AlCl3). The synthesis and characterization of these complexes are exemplified.<p> Also illustrated in this thesis is the synthesis and characterization of a series of air- and moisture-stable iminoisoindoline-based palladacyclic compounds of the general formula, [(iminoisoindoline)Pd{Ý-OAc}]2. These six-membered palladacyclic complexes were obtained through a simple two-step protocol as analytically pure solids. Phosphine-ligated mononuclear palladacycles of the general formula, [Pd(iminoisoindoline)X(PR3)], X= OAc or Cl, R = Ph or Cy, are also described. Dinuclear palladacycles were also found to be active for the Heck and Suzuki C-C coupling reactions. TONs of up to 106, 105 and 60 were observed for coupling of iodobenzene, <i>p</i>-acetylbromobenzene and <i>p</i>-chlorobenzaldehyde, respectively in the Heck coupling reaction.

The research in this thesis involves the synthesis and characterization of nanoparticle catalysts for oxidation reactions. It includes two projects: 1) polymer-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts for alcohol oxidation reactions, and 2) oxidative stabilities and catalytic activities of thiolate- and dithiolate-protected Au monolayer-protected clusters (MPCs).<p>n the first project, alcohol oxidations under mild conditions using polyvinylpyrrolidone (PVP)-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts in aqueous solutions have been investigated. The catalytic activities of the nanoparticles towards the oxidation of benzyl alcohol, 1-butanol, 2-butanol, 2-buten-1-ol and 1,4-butanediol indicate that bimetallic 1:3 Au:Pd nanoparticles have higher catalytic activities than Au, Pd and other bimetallic AuPd nanoparticles, and that selectivities towards specific products can often be tuned using bimetallic particles. In addition, advantages and disadvantages for the use of such nanoparticle catalysts as mild, environmentally-friendly oxidation catalysts have been examined. This work has recently been published in the Journal of Catalysis.<p>In the second project, 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs have been synthesized and their thermal stability, oxidative stability in the presence of oxygen and cyanide anions have been studied. These systematic investigations reveal the stability of Au MPCs can be tuned by choosing different thiolate ligands and oxidation conditions. Partially-oxidized thiolate-protected Au MPCs which have substrate-accessible surfaces and are stabilized by residual thiolate ligands show indications they will be promising catalysts. The catalytic activities of 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs for catalytic 4-nitrophenol reduction with sodium borohydride were investigated, and all the Au MPCs showed high catalytic activity for this reaction.

The regioselectivity in Pd(0)-catalyzed direct arylation of pyrrole, thiophene, and indole can be improved by blocking some of the reactive sites with a chloride group, leading to increased yields of the desired regioisomers. Competition experiments and computational studies show that the blocking group also activates the substrates toward arylation. Due to the activated nature of chlorinated heteroaromatics, rare and sought after regioisomers, such as 3-arylthiophenes, can be obtained under mild conditions in good yields. Chlorine-bearing thiophenes arylated at C3 and C4 have the potential to undergo controlled regioregular polymerization under conditions developed in the field of polythiophene chemistry. Mechanistic studies support the hypothesis that the arylation of the substrates under investigation likely proceeds via the CMD transition state.

Fluorocarbons (FCs) and their derivatives (FCDs) are heavily relied on due to their wide range of uses (e.g. solvents, surfactants, refrigerants, and pharmaceuticals). Currently, FCs and FCDs are produced on an industrial scale via energy-intensive processes, using hazardous materials. Hence, new catalytic chemical technologies are required to provide cleaner and greener synthetic routes to partially fluorinated materials. The exploration of fundamental organofluorometallic chemistry of base metals, such as nickel, has potential to advance the development of novel catalytic processes towards this end. It has been established previously that zero-valent nickel complexes have the ability to efficiently catalyze the hydrodimerization of polyfluoroalkenes. The reactivity of the intermediate polyfluoronickelacycles was found to be influenced by modifications in the ligand sphere. Furthermore, an increase in oxidation state of the central metal atom was proposed as an additional strategy to increase the reactivity of the M-RF bond. In this thesis, through variation of the ligand environment and oxidation state of nickel, we have further developed the chemistry of high-valent polyfluoronickelacycles. Synthesis and characterization (NMR, EPR, UV/Vis, IR spectroscopy and electrochemistry) of new trivalent polyfluoronickelacycles are described as well as attempts to generate the corresponding tetravalent cations. Attempts to induce nucleophilic insertion of acetonitrile into the Ni-RF bond were also investigated herein. Challenges were encountered with the isolation of the tetravalent cations due to decomposition to the corresponding divalent nickelacycle.

La tesis presentada es un estudio basado en la síntesis, caracterización espectrocópica y electroquímica y aplicaciones en catálisis de nuevos complejos mononucleares de rutenio con una amplia variedad de ligandos polipiridílicos. La influencia de las propiedades electrónicas de los ligandos coordinados al centro metálico sobre las propiedades redox de los complejos resultantes y su comportamiento en catálisis de oxidación ha sido estudiada y racionalizada. De la familia de complejos Ru-OH2 sintetizados y estudiados, unos pocos fueron seleccionados para desarrollar sistemas más complejos y poder ser utilizados para (a) catálisis heterogénea (obteniendo sistemas catalíticos fácilmente reciclables) y (b) catálisis supramolecular (para poder llevar a cabo oxidaciones regioselectivas de sustratos orgánicos). Para el desarrollo de catálisis heterogénea, nanopartículas magnéticas (NPs) de óxidos de hierro fueron seleccionadas como soporte y los sistemas resultantes NP-Ru presentaron una buena dispersión en disolventes orgánicos y pudieron ser fácilmente separados y reutilizados, obteniendo así un sistema casi-homogéneo, en el que las ventajas de ambos procesos homogéneo y heterogéneo fueron combinados. Como último capítulo de la tesis, se presenta la introducción de quiralidad en el sistema catalítico mediante la utilización de un nuevo ligando tipo pineno tridentado quiral. / The PhD thesis presented deals with the synthesis, thorough spectroscopic and electrochemical characterization and catalytic application of new mononuclear RuII-OH2 complexes containing a wide set of N- and O-donor ligands. The key influence of the electronic properties of the surrounding ligands on the redox chemistry of the resulting complexes and in the final output of catalytic oxidation reactions has been studied and rationalized. From the wide set of exhaustively studied Ru-OH2 catalysts a few were selected in order to develop more complex systems to be used in (a) heterogeneous catalysis (gathering easily recyclable catalytic systems) and (b) supramolecular catalysis (in order to pursue the regio-selective oxidation of complex organic substrates). For the development of heterogeneous catalysis magnetic nanoparticles (NPs) were chosen as support and the resulting Ru-NP systems presented good dispersion in organic solvents and could be easily removed and recycled, reaching a quasi-homogeneous system in which the advantages of both homogeneous and heterogeneous processes were combined. Furthermore, the introduction of chirality into the catalytic systems was also performed in the last chapter through a new chiral pineno-fused tridentate ligand.

Cocatalyzed reactions using Brønsted acids and chiral N-heterocyclic carbenes to yield highly enantioselective products have been reported recently in many journals. The development of new chiral N-heterocyclic carbenes is a competitive field among synthetic chemist. In a recent study we found that conjugated trienes could be cyclized using Brønsted acids and chiral N-heterocyclic carbenes. The synthesis of novel chiral N-heterocyclic carbene precursors, and the precursors to novel conjugated trienes are reported herein.

Increases in vehicle exhaust emission regulations have led to research, development and improvements in catalytic converter technologies for gasoline-powered vehicles since the 1970s. Nowadays, there are strict regulations and standards for diesel engines as well, and one of the regulated species is nitrogen oxides (NOX). The lean NOX trap (LNT) catalyst has been studied and developed for use in lean burn (of which diesel is an example) engine exhaust as a technology to reduce NOX to N2. Typical LNT catalysts contain Pt, which catalyzes NO oxidation and NOX reduction, and an alkali or alkaline earth material for NOX storage via nitrate formation. The catalyst is operated in a cyclic mode, with one phase of the cycle under oxidizing conditions where NOX is trapped, and a second phase, which is reductant-rich relative to O2, where stored NOX is reduced to N2. A recently developed catalyst uses a perovskite material as part of the LNT formulation for the oxidation reactions thereby eliminating the need for Pt in a LNT. This catalyst does include Pd and Rh, added to accommodate hydrocarbon oxidation and NO reduction, respectively. Ba was used as the trapping component, and Ce was also part of the formulation. NO oxidation kinetics over the fully-formulated and bare perovskite material were determined, with NO, O2 and NO2 orders being at or near 1, 1 and -1, respectively for both samples. The fully-formulated sample, which contains Ba supported on the perovskite, was evaluated in terms of NOX trapping ability and NOX reduction as a function of temperature and reduction phase properties. Trapping and overall performance increased with temperature to 375°C, primarily due to improved NO oxidation, as NO2 is more readily trapped, or better diffusion of nitrates away from the initial trapping sites. At higher temperatures nitrate stability decreased, thus decreasing the trapping ability. At these higher temperatures, a more significant amount of unreduced NOX formed during the reduction phase, primarily due to nitrate instability and decomposition and the relative rates of the NOX and oxygen storage (OS) components reduction reactions. Most of the chemistry observed was similar to that observed over Pt-based LNT catalysts. However, there were some distinct differences, including a stronger nitrate diffusion resistance at low temperature and a more significant reductant-induced nitrate decomposition reaction. The perovskite-based lean NOX trap (LNT) catalyst was also evaluated after thermal aging and sulfur exposure. NO oxidation, NOX trapping ability and NOX reduction as a function of temperature and reduction phase properties were evaluated. Similar overall performance trends were seen before and after degradation, however lower performance after thermal aging and sulfur exposure were seen due to sintering effects and possible build-up of S species. Although performance results show that most of the sulfur was removed after desulfation, some sulfur remained affecting the trapping and reduction capabilities as well as the water gas shift (WGS) extent at lower temperatures. The Oxygen storage capacity (OSC) on the other hand was maintained after the catalyst was exposed to thermal aging and sulfur poisoning then desulfation, all of which suggest that the perovskite or Pd components were irreversibly poisoned to some extent.