Monovalent coinage metal complexes have been of significant interest due to their rich photophysical properties. This dissertation focuses on the design, synthesis, and characterization of gold, silver, and copper phosphors. Chapter 2 investigates new physical and photophysical properties of a gold diphosphine dimer in the solid state. Thermally activated luminescence switching between two structural states is discussed. Chapter 3 includes the photochemistry of closed shell group 11 transition metals with dithiophosphonate and diphosphine ligands as heteroleptic, homoleptic and heterometallic systems. Chapter 4 reports the synthesis and characterization of a cyclic trinuclear gold imidazolate complex with high electron dentistry and π- base properties. The trinuclear gold (I) complexes reactivity with silver(I) and sodium cations is explored. The photochemistry of all complexes are screened for efficiency, emission profiles and lifetimes as potential materials to be used in OLEDs and other molecular devices.

Coinage metals such as copper, silver and gold have captivated mankind with their desirable qualities and social value. Recently, these metals have peaked the interests of scientists, where organic chemists have used them extensively in the homogenous catalysis of organic transformations. In our laboratory, we exploited their π-Lewis acidic properties to activate alkyne to induce intramolecular cyclization of nucleophilic enol ethers. We discovered that modulating the steric and electronic profiles of the ancillary ligand on the cationic metal complexes allowed for the regioselective control of such reactions. During the exploration of the substrate dependency of these transformations, we discovered that unsubstituted alkynes undergo a 6-endo-dig/acetalization/Prins reaction cascade in the presence of a silver salt such as [(BrettPhos)Ag(MeCN)]SbF6, resulting in the formation of highly strained polycycles. We have demonstrated that the formation of these products is initiated by a selective 6-endo-dig cyclization. Further mechanistic studies suggested that the reaction may occur through silver dual catalysis using deuterium-labelling experiments, however, single activation of the starting material would lead to the same product and thus both mechanisms were proposed. The further reactivity of these interesting polycyclic products was also explored. Total synthesis of natural products is often referred to as an art, as it defines the boundaries of organic chemistry. In our laboratory, we have always been interested in the challenge of ingeniously building architecturally complex molecules. With the development of optimized conditions for the selective formation of decaline cores from silylenol ethers, the application of this methodology to the synthesis of teucrin A was sought. Our synthetic approach is highlighted by a sequential Diels-Alder/6-endo-dig cyclization reaction to rapidly assemble the clerodane diterpenoid framework of the natural product. To that end, the synthesis of the target utilized a strategy featuring a Diels-Alder reaction between an exocyclic allene and a silyl enolether, which proceeded in 59% yield at 110°C with a diasteomer ratio of 3:1. Unfortunately, attempts to induce the [4+2] cycloaddition using Lewis acids that were vital to the proposed synthetic route led to either no conversion or hydrolysis of starting material. Since this key step proved challenging, alternative synthetic pathways are currently being investigated in our group. Since the elucidation of its molecular structure by Robinson in 1925, morphine has received tremendous attention from the synthetic community. Indeed, about 50 formal and total syntheses of morphinans have been reported since the original synthesis by Gate in 1952. Herein, the synthetic efforts achieving a 9-step formal synthesis of (±)-morphine from readily available starting materials such as o-vanillin is presented. This synthesis features the quick assembly of the phenanthrofuran framework of the natural product in only five steps. The tetracyclic intermediate was synthetized through the careful orchestration of a Diels-Alder/elimination/deprotection sequence as well as a telescopic Claisen rearrangement/Friedel-Crafts alkylation. Subsequent strategic functional group manipulations allowed us to reach the advanced compound in four more steps and thus intercepting a known intermediate, which required two additional chemical transformations to form morphine. Overall, the work presented in this thesis represents the development of innovative methods for the creative disconnection of natural products. These advancements promote the rapid assembly of molecular cores found in many bioactive molecules.

The prevalence of fluorine in natural products is scarce. There are but a handful of compounds that have been discovered to date. This could be largely attributable to the occurrence of fluorine in nature as fluoride (F-). — One might recognize such nomenclature from the ingredients list on a toothpaste tube — In fact, naturally occurring fluoride is most commonly found as fluorite (CaF2) or cryolite (Na3AlF6). As such, the introduction of fluorine via biological pathways has been limited to use of aqueous F- (a very poor nucleophile). This fact — coupled with its naturally low concentration in water — has created the ripe conditions for this shortage. In a way this has proven fertile for synthetic chemists because nature has not yet evolved a method for the deconstruction of partially or fully fluorinated compounds. Considering the above, as synthetic methodologies for the construction of carbon-fluorine bonds became available, so too did the discovery of their valuable properties. So beneficial are these properties that C-F bond-containing compounds have become commonplace in many households throughout the world. For example, practically every home relies on these compounds for use in their refrigerators. Other examples of useful fluorinated materials include blowing agents, non-stick coatings, pharmaceuticals, agrochemicals, liquid crystals, and lubricants. With all these applications and seemingly easy availability of these compounds, it is interesting to learn that original synthetic methods are still being employed today. As such, the objective of this Thesis is to develop ‘greener’ routes for the synthesis of fluorocarbons. We hypothesized that by studying transition metal-fluoroalkyl complex-mediated reactions, a more efficient catalytic system could be developed. A foreseen complication arises from the thermodynamic stability of C-F, transition metal-F and transition metal-CRF bonds. Improvements to overcome these caveats include the use of first-row late transition metal complexes. Presented herein are additions to this body of knowledge by expanding on the reactivity of nickel, copper and silver fluoroalkyl complexes. The approach applied in this work, in line with ‘green’ chemistry principles, was to source readily available fluorinated reagents, i.e. fluoroalkenes and fluoroarenes, to reduce the number of steps for the synthesis of new fluorinated compounds. Chapter 2 builds on the well-established oxidative cyclization of C2 fluoroalkenes to nickel (0), which yields new C4 units. The use of a bulky N-heterocyclic carbene ligand was found to enhance reactivity by reducing the coordination number at nickel. Examples of room temperature Cα-F and Ni-CF bond activation and functionalization reactions are presented. Chapters 3, 4 and 5 re-examine the insertion of fluoroalkenes into silver and copper fluorides and hydrides. Building on precedent of addition reactions to hexafluoropropene, this fluoroalkene was examined first. In so doing, a versatile and inexpensive copper heptafluoroisopropyl reagent was developed (Cu-F addition to (CF3)CF=CF2. With easy access to new heptafluoroisopropyl complexes, they were systemically studied for their applications in catalysis. This revealed key features, particularly the lability of the M-hfip bond, which could be detrimental to catalytic reactions. As such, a nickel complex-mediated carbonylative heptafluoroisopropylation reaction and copper complex-mediated nucleophilic addition to electrophiles were developed. When a copper hydride was used instead, the in situ generated fluoroalkyl [Cu-H addition to (CF3)CF=CF2] was susceptible to β-fluoride elimination. Chapter 4 expands this methodology to achieve the catalytic consecutive hydrodefluorination of fluoroalkenes, demonstrating the scope and limitations of this system. Furthermore, the critical role of the phosphine ligand in accessing an L3Cu-H addition and unusual β-fluoride elimination mechanism is highlighted. However, tetrafluoroethylene proved resistant to this reaction because the fluoroalkyl resting state of this alkene, Cu-CF2CF2H, is unusually robust. Chapter 5 investigates the utility of this fragment and others in C(sp2)-RF cross-coupling and nucleophilic substitutions. With focus on new routes for late stage fluorination and examples of nickel (0) complex-catalyzed selective C-F bond functionalization reactions, Chapter 5, continues studies for low-temperature and DMAP-assisted conditions for aryl-F cross-coupling reactions with boronic acid esters. Lastly, Chapter 6 reviews the advances presented in this Thesis, provides a link to the expected lasting impacts and attempts to provide guidance to future research on transition-metal complexes in the synthesis of C-F or C-RF containing compounds. Moreover, with the introduction of a new hydrodefluorination technology, previously scarce fluoroalkenes (e.g. 1,2-difluoroethylene) can now be used more freely, potentially leading to the development of new refrigerants or materials applications.

Computational chemistry employs mathematical algorithms, statistics, and large databases to integrate chemical theory with experimental observations. Computational modeling allows us to make predictions concerning molecular properties and reactivity that ultimately lead to accurate assessment of the most important fundamental properties of chemical systems. Advances in theoretical techniques and computer power have dramatically increased the usefulness and importance of computational chemistry as a complement to experimental studies. This is especially relevant to catalytic reactions of industrial importance as well as the analysis of structural properties and the resulting spectroscopic phenomena in what are often otherwise counterintuitive models. This dissertation is a representation of the research I performed during my years as a graduate student in the Chemistry Department at the University of North Texas. My research has examined novel carbenes as efficient organocatalysts, structure-based design and optimization of small molecule drugs, and surveying methods to accurately describe structure and bonding and catalytic abilities of inorganic and organometallic systems. The works presented herein have been published or are awaiting submission to peer-reviewed scientific journals. A variety of computational techniques were employed in studying metal-mediated catalysis and organocatalysis as well as the structural and photophysical properties of systems containing closed-shell transition metal ions.

No description available.

Les carbènes N-hétérocycliques (NHC) sont utilisés comme ligands pour les métaux de transition. Les complexes résultants présentent principalement des applications en catalyse, ainsi que dans la conception de nouveaux candidats médicaments. Dans ce travail, nous discuterons une simplification des méthodes de synthèse des sels d’imidazoliniums, ainsi que des complexes Cu- et Ag-NHC. L’ammoniaque est utilisé ici à la fois comme milieu solubilisant des espèces métalliques et comme base pour la déprotonation des sels d’imidazoli(ni)ums fournissant une métallation douce, rapide et simple. La fonctionnalisation des NHC, dans des positions définies, permet une modulation de certaines de leurs caractéristiques sans impacter les propriétés remarquables de leurs complexes. De nouvelles méthodes de fonctionnalisation, par cycloaddition azoture-alcyne en périphérie des noyaux aromatiques, ont été mises au point. Ceci mène à l’introduction de trois stratégies synthétique : pré-, post- et auto-fonctionnalisation. La stratégie de pré-fonctionnalisation de précurseurs permet l’accès à des métallo-NHC du groupe 11, dont les propriétés de solubilité peuvent être facilement modifiées. Des réactions thermiques d’Huisgen et de SPAAC sont réalisables directement sur les complexes Au-NHC modifiés par des azotures, et sont désignés comme post-fonctionnalisation. Des réactions dites d’auto-fonctionnalisations entre un complexe Cu-NHC possédant un azoture et des alcynes divers, permettent l’introduction, par exemple, de biomolécules sensibles sans étapes de protection/déprotection. Enfin, les complexes Cu-NHC fonctionnalisés avec des groupements hydrosolubilisants ont été étudiés en tant que catalyseurs de cycloaddition de CuAAC dans des milieux biocompatibles, tandis que les Ag-NHC fonctionnalisés avec des groupements lipophiles présentent une activité antibactérienne. / N-heterocyclic carbenes (NHCs) have been used very frequently as ligands for the preparation of transition metal-based catalysts as well as drug candidates. This work will present a simplification of imidazoliniums synthesis and a new preparation of Ag-, Cu-NHC complexes. Aqueous ammonia will be used for the solubilisation of metallic species and as a base for the deprotonation of imidazoli(ni)um salts providing a mild, quick and easy metallation procedure. The functionalisation of NHC ligands, in definite positions, allows the modulation of some of their characteristics without interfering with the remarkable properties of their complexes. New functionalisation strategies by azide-alkyne cycloaddition reaction at the periphery of aromatics cores, were developped. This can be described by the following three synthetics strategies: pre-, post- and auto-functionalisation. Pre-functionnalisations strategy of precursors allows the synthesis of coinage metal-NHC complexes, for which variation of solubility is easily obtained. Thermal Huisgen reactions and SPAAC are achievable on the Au-NHC azide modified complexes directly, in a post-functionalisation pathway. Furthermore, the post-functionnalisation strategy was extended to Cu-NHC complexes resulting in an auto-functionalisation process. This allowed subsequently the introduction of sensitive biomolecules without protection/deprotection steps. Finally, water soluble Cu-NHCs complexes were used as CuAAC catalyst in bio-compatible media. Lipophilic Ag-NHCs complexes were tested as antibacterials (antibiofilm and growth inhibition activities).

Computational chemistry has gained interest as a characterization tool to predict photoluminescence, reactivity and structural properties of organic and transition metal complexes. With the rise of methods including relativity, these studies have been expanded to the accurate modeling of luminescence spectra of complexes with considerable spin-orbit splitting due to heavy metal centers as well as the reaction pathways for these complexes to produce natural products such as hydrogen gas. These advances have led to the synthesis and utility of more effective catalysis as well as the development of more effective organic light emitting diodes (OLEDs) through the incorporation of organometallic complexes as emitters instead of typical organic emitters. In terms of significant scientific advancement presented in this work is in relation to the discovery of significant spin-orbit splitting in a gold(I) alkylphosphine complex, where the splitting results in the states that emit in different colors of the visible region of the electromagnetic spectrum. This work also reveals the discovery both computationally and experimentally, of a genuine polar-covalent bond between two-closed shell metals. This work highlights a complex with an incredibly short gold(I) – copper(I) intermetallic distance leading to a vibrational frequency and dissociation energy that is on par with those of other systems with single-bonded metal centers. Lastly, this work outlines a strategy for the production of hydrogen gas through the use of trinuclear cyclic coinage metal complexes as catalysis to split hydrohalic acids.

Les polymères de coordination (PCs) à base de thiolates de métaux monétaires sont bien connus pour leurs propriétés luminescentes. Cependant, leurs structures sont sous-explorées. Dans cette thèse, nous présentons une étude pionnière visant la compréhension de la formation de la structure et de la corrélation ‘structure-propriétés’ des PCs homoleptiques neutres, [M(SR)]n, M = Cu(I), Ag(I), Au(I). Les composés avec les dérivés du thiophénolate étudiés dans ce travail, illustrent comment l'utilisation de certains ligands organiques fonctionnalisés conduit à la formation de réseaux 2D étendus ou de colonnes 1D par l'addition d'un encombrement stérique. De plus, la première étude structurelle comparative des PCs thiolées amorphes a été réalisée par analyse PDF. Les études photophysiques ont montré la diversité des propriétés luminescentes des PCs à base de thiolates de métaux monétaires. Des pics d'émission doubles ou multiples, un rendement quantique élevé, des émetteurs orange à proche infrarouge, des variations significatives de durée de vie en fonction de la température... toutes ces propriétés intrinsèques révèlent le potentiel élevé de ces composés pour diverses applications optiques / The coordination polymers (CPs) based on thiolates of coinage metals are well known for their luminescence properties. However, their structures stayed underexplored. In the thesis we present a pioneering study targeting the understanding of the structure formation and the ‘structure-properties’ correlation for neutral homoleptic CPs, [M(SR)]n, M = Cu(I), Ag(I), Au(I). The compounds with thiophenolate derivatives studied in the work, illustrate how the use of some functionalized organic ligands leads to the formation of extended 2D networks or 1D columns by addition of some steric hindrance. The first comparative structural study of amorphous thiolated CPs was performed by PDF analysis. The photophysical studies showed the diversity of luminescent properties of the CPs based on thiolates of coinage metals. Double or multiple emission peaks, high quantum yield of orange-toinfrared emitters, significant lifetime variation with temperature… all of these intrinsic properties reveal the high potential of these compounds for diverse optical applications