This dissertation involves inorganic/organometallic catalysis models, in particular the functionalization of carbon-hydrogen and carbon-carbon bonds. Computational methods have been utilized to better understand the factors affecting the kinetics and thermodynamics of C−H and C−C bond activation/functionalization in this dissertation. Chapter 2 investigates methane C−H activation with a diiminopyridine nitride/nitridyl complex of 3d transition metals and main group elements via three competing pathways: 1,2-addition/[2 + 2] addition, insertion and H-atom abstraction/proton coupled electron transfer. Chapter 3 investigates a transition metal catalyzed C=C bond functionalization involving C−N bond formations to synthesize aziridines from aromatic and aliphatic alkenes. The study focuses on anionic 3d transition metal (M = Mn, Fe, Co and Ni) triphenylamide-amine complexes with nitrene active intermediates for the aziridination reactions. Chapter 4 investigates a disphenoidal Ni(II) azido complex participating in intramolecular C−H functionalization and amination via a putative Ni nitridyl intermediate and a 1,2-addition/[2 + 2] addition pathway. In Chapter 5, methane oxidative addition to the Cp*ML (Cp* = η5-C5Me5; M = Co, Rh, Ir , L = CO, PMe3) motif is compared and contrasted when the classic CO and PMe3 ligands are replaced with the cyclic alkyl(amino) carbene (CAAC) as ancillary ligands.

The first project in this thesis describes our research reacting arynes with tertiary allyl amines to generate functionalised anilines via a benzyne induced aza-Claisen reaction. This process works in good to excellent yields and the methodology can be further applied to make benzannulated medium sized ring amine systems. The second project covered in this thesis details our studies in the generation of benzyne from benzoic acid. This process utilises palladium catalysis involving an ortho C-H activation of benzoic acid which generates a 5 membered palladacycle. This palladacycle then spontaneously decomposes with heat to generate palladium bound benzyne and carbon dioxide. The yield of benzyne was monitored by observing the amount of triphenylene formed in the process. Further synthetic applications in this process were limited, but it was shown that the benzyne could be reacted with alkynes to generate phenanthrene and naphthalene products. The third project in this thesis details our work on the insertion of benzyne into the C–S bond of thioesters. Using palladium catalysis and an o-trimethylsilylphenyl triflate benzyne precursor, a variety of thioethers were produced. The yields for this reaction were moderate to good but it was found that only aromatic substituents were tolerated on the thioester.

This thesis is divided into two main chapters, which are focused on two separated and uncorrelated research areas. The first part of this thesis is dedicated to the research I carried out in benzyne chemistry and the second part is focused on catalytic C-H bond activation. In the first place, a novel insertion reaction of arynes into the nitrogen-carbonyl σ-bond of amides has been investigated as a rapid and powerful approach for the preparation of valuable ortho-disubstituted arenes. Readily available aromatic amides undergo smooth insertion when treated with O-triflatophenyl silane aryne precursors, producing versatile anthranilic derivatives in good to excellent yields. The process is entirely metal-free and has been expanded to the synthesis of biologically active heterocycles such as acridones and acridines. Secondly, the synthesis of medium-sized ring systems by intramolecular oxidative CH bond coupling has been explored. Despite the abundance of biologically active natural products featuring mediumsized rings, the synthesis of such ring systems using classical synthetic routes faces many challenges and has led to a dearth of medium ring compounds in medicinal chemistry. In contrast to the more facile 5-membered ring synthesis by oxidative C-H coupling, medium ring synthesis has not been previously reported using this approach. The chemistry, which requires zero pre-functionalisation of the substrates, is catalysed by palladium and has been exemplified using heteroaromatic substrates at the core of numerous biologically active molecules. The mechanism of the reaction has also been studied and a catalytic cycle has been proposed.

Catalytic, selective C-H bond activation for the oxidative hydroxylation RH → ROH of simple or complex compounds is of significant interest in synthetic organic chemistry. One of the major classes of enzymes used for C-H bond activation are cytochrome P450 monooxygenases (EC 1.14.X.X), which can promote chemo-, regio- and stereoselective oxidations under mild reaction conditions. For the current study, catalytically self-sufficient forms of biocatalyst P450cam-RhFRed were investigated. These self-sufficient P450 systems were previously created by fusing the reductase domain of P450 RhF (CYP116B2, RhFRed from Rhodococcus sp.) with the catalytic domain of P450cam (CYP101A1, Pseudomonas putida), thus mimicking the natural fusion of P450 RhF. The generation of 93 P450cam-RhFRed variants has expanded the synthetic toolbox to serve as a basis for exploring the substrate scope towards ethylbenzenes, substituted alkylbenzenes, 4-ethylphenol and (+)-pleuromutilin. To select for active mutants from this library of 93, high throughput screening methods were developed. A pooling approach was applied in order to express P450s and analyse them against a panel of non-natural substrates, such as ethylbenzene, 4-ethylphenol and (+)-pleuromutilin in whole cell biotransformation reactions. The concentration of P450 enzymes was determined using CO difference spectroscopy in whole cells. The assay was significantly improved both in terms of speed and safety by using carbon monoxide releasing molecules as a source of CO rather than the gas CO itself. These screening studies served as starting point to identify P450cam-RhFRed mutants for specific reactions. In particular, a systematic investigation of this library showed mutants that generated chiral benzyl alcohols with good enantioselectivities. To interpret these results on a structural basis, molecular dynamics simulations were used to estimate enantioselectivity of selected mutants for the regio-isomers of methylated ethylbenzene derivatives. The results from the molecular dynamics simulations were broadly consistent with experimentally determined data and identified the importance of conformational changes and flexibility of mutant-substrate complexes to enforce enantioselectivity.

1. Benzene C-H Activation by Nickel(II) and Platinum(II) Complexes of Chelating Diarylamido Phosphine Ligands We have demonstrated an efficient intermolecular benzene C-H activation process mediated by Ni(II) complexes of ([Me-NP-iPr]Ni(L)(R)(L = Pyridine, 2,4-Lutidine, PMe3) and [iPr-NP-Ph]Ni(PMe3)(R) (R = Me, CH2SiMe3). When Lewis base is PMe3 or substituent is CH2SiMe3 more reactivity is observed. The amido diphosphine complexes [iPr-PNP]PtOTf effectively activate the benzene C-H bond in the presence of an appropriate Lewis base(NEt3 or DABCO). 2. Metal Complexes of Amido Phosphine Ligand Bearing Unsymmetric Donor Atom: Syntheses, Structures and Reactivities A series of [Ph-PNN]Ni(II)R (R = Me, Et, Ph, CH2Ph) complexes containing £]-hydrogen atoms have been prepared and characterizated. We have demonstrated an efficient intermolecular arene C-H activation process mediated by Ni(II) complexes of [Ph-PNN]NiEt at elevated temperature. A series of nickel(II) complexes featuring an unsupported, covalently bound p-donor ligand including anilide, phenolate, thiophenolate and tert-butoxide derivatives have been prepared and characterizated. Novel unsymmetric tridentate ligands (H[R-PNO], R = iPr, Ph) have been prepared and characterized. The reaction of [iPr-PNO]NiCl with Na/Hg in thf or ether at room temperature induced C-O bond activation followed by the generation of {[iPr-PNO]Ni}{[iPr-PNO*]NiMe}. 3. Amido Diphosphine Complexes of Cobalt: Syntheses, Structures and Reactivities A series of paramagnetic divalent cobalt complexes ([R-PNP]CoCl, R = iPr, Cy) supported by tridentate diarylamido phosphine ligands have been prepared and characterized. The diamagnetic monovalent cobalt-dinitrogen complexes ([R-PNP]Co(N2), R = iPr, Cy) are accessible from the reaction of [R-PNP]CoCl with LiHBEt3 in THF solution. The dinitrogen complex [Cy-PNP]Co(N2) reacts in THF with terminal alkynes, HC¡ÝCR, yielding vinylidene complexes ([Cy-PNP]Co=C=C(H)(R), R = Ph, SiMe3). The dinitrogen complex [Cy-PNP]Co(N2) and {[iPr-PNP]Co}2(£g-N2) reacts in THF with diphenylacetylene (PhC¡ÝCPh) yielding p complexes ([R-PNP]Co(h2-PhC¡ÝCPh), R = iPr, Cy). 4. Fluorinated Mono- and Diarylamido Complexes of Lithium and Group 4 Metals The synthesis of bis-ligand Group 4 metal complexes ([iPrAr-NF]2MCl2, M= Zr, Hf) are utilizing [iPrAr-NF]Li and MCl4(THF)2. The alkylation of [iPrAr-NF]2MCl2 with RMgCl (R= Me, iBu, PhCH2, Me3SiCH2) produced a series of group 4 metal complexes ([iPrAr-NF]2MR2, M= Zr, Hf) which are catalyst precursors for olefin polymerization. Deprotonation of H[iPr-NF] and H[Cy-NF] with n-BuLi in ethereal solutions at -35 ¢XC produced the lithium complexes {[iPr-NF]Li(solv)}2 (solv = THF, Et2O) and {[Cy-NF]Li(Et2O)}2, respectively. The metathetical reaction of [iPr-NF]Li(Et2O) with 1/3 equiv TiCl4(THF)2 in toluene solution produced the trianilide titanium complex [iPr-NF]3TiCl. A series of novel fluorinated bidentate (H[Mes-NP-RF], R = iPr, Ph) and tridentate ligands (H2[Mes-NPNF]) have been prepared and characterizated.

Thermolysis of Cp*W(NO)(CH₂CMe₃)₂ (2.1) in halo, methoxy, or phenylethynyl-substituted benzenes leads to the formation of the alkylidene intermediateCp*W(NO)(=CHCMe₃) which selectively activates ortho C-H bonds of the organicsubstrates. The ortho-regioselectivity diminishes as the size of the substituent increasesfrom F (97 %) to C-=CPh (51 %). In the solid-state structure of all complexes the ortho-substituent is not coordinated to the metal centre; rather, the metal centre is engaged inagostic interactions with a neopentyl methylene C-H bond. Mechanistic studies on the chlorobenzene reaction reveal that the ortho-C-H-activation product is preferentially formed via thermal isomerization from the meta / para-C-H-activation isomers. Reactions between Cp*W(NO)(CH₂EMe₃)Cl (E = C or Si) and a variety of bis(allyl)magnesium reagents lead to the expected formation of Cp*W(NO)(alkyl)(allyl)complexes. Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCH₂) (3.5), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CMeCH₂) (3.6), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7),Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) and Cp*W(N0)(CH₂SiMe₃)(η³-CH₂CHCHMe) (3.9) have thus been synthesized in moderate yields. The solid-state molecular structures of 3.5 and 3.7-3.9 feature a σ-π distorted ally! ligand in the endoconformation. Complex 3.5 reacts with pyrrolidine at RT to form Cp*W(NO)(NC₄H8)(CHMeCH₂NC₄H8) (3.10), a nucleophilic-attack product. Complexes 3.6-3.9 effect the concurrent N-H and α-C-H activation of pyrrolidine at RT and form alkyl-amido complexes analogous to the previously known Cp*W(N0)(CH₂EMe)(NC₄H₇-2-CMe₂CH=CH₂) (3.12). Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7) at RT leads to the loss of neopentane and the formation of the η²-diene intermediate Cp*W(N0)(η²-CH₂=CHCH=CH₂) (A) which has been isolated as a PMe₃ adduct. In the presence of saturated organic substrates, C-H activation occurs exclusively at the methyl positions of the molecule. Reactions between intermediate A and unsaturated substrates lead to coupling between the coordinated η²-diene and the unsaturation on the organic molecule.Treatment of Cp*W(N0)(n-C₅H₁₁)(η³-CH₂CHCHMe) (4.1) with I₂ at -60 °C produces n-C₅H₁₁ I in moderate yields. Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) in benzene at 75 °C for one day leads to the exclusive formation of Cp*W(N0)(H)(η³-PhCHCHCHPh) (5.1).Trapping, labelling, and monitoring experiments suggest that 5.1 is formed via 1) the loss of neopentane and the generation of the allene intermediate Cp*W(N0)(η²-CH₂=C=CHPh), 2) the C-H activation of benzene resulting in a phenyl phenylallyl complex, and 3) the thermal isomerization of this latter species to 5.1.

Thermolysis of Cp*W(NO)(CH₂CMe₃)₂ (2.1) in halo, methoxy, or phenylethynyl-substituted benzenes leads to the formation of the alkylidene intermediateCp*W(NO)(=CHCMe₃) which selectively activates ortho C-H bonds of the organicsubstrates. The ortho-regioselectivity diminishes as the size of the substituent increasesfrom F (97 %) to C-=CPh (51 %). In the solid-state structure of all complexes the ortho-substituent is not coordinated to the metal centre; rather, the metal centre is engaged inagostic interactions with a neopentyl methylene C-H bond. Mechanistic studies on the chlorobenzene reaction reveal that the ortho-C-H-activation product is preferentially formed via thermal isomerization from the meta / para-C-H-activation isomers. Reactions between Cp*W(NO)(CH₂EMe₃)Cl (E = C or Si) and a variety of bis(allyl)magnesium reagents lead to the expected formation of Cp*W(NO)(alkyl)(allyl)complexes. Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCH₂) (3.5), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CMeCH₂) (3.6), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7),Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) and Cp*W(N0)(CH₂SiMe₃)(η³-CH₂CHCHMe) (3.9) have thus been synthesized in moderate yields. The solid-state molecular structures of 3.5 and 3.7-3.9 feature a σ-π distorted ally! ligand in the endoconformation. Complex 3.5 reacts with pyrrolidine at RT to form Cp*W(NO)(NC₄H8)(CHMeCH₂NC₄H8) (3.10), a nucleophilic-attack product. Complexes 3.6-3.9 effect the concurrent N-H and α-C-H activation of pyrrolidine at RT and form alkyl-amido complexes analogous to the previously known Cp*W(N0)(CH₂EMe)(NC₄H₇-2-CMe₂CH=CH₂) (3.12). Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7) at RT leads to the loss of neopentane and the formation of the η²-diene intermediate Cp*W(N0)(η²-CH₂=CHCH=CH₂) (A) which has been isolated as a PMe₃ adduct. In the presence of saturated organic substrates, C-H activation occurs exclusively at the methyl positions of the molecule. Reactions between intermediate A and unsaturated substrates lead to coupling between the coordinated η²-diene and the unsaturation on the organic molecule.Treatment of Cp*W(N0)(n-C₅H₁₁)(η³-CH₂CHCHMe) (4.1) with I₂ at -60 °C produces n-C₅H₁₁ I in moderate yields. Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) in benzene at 75 °C for one day leads to the exclusive formation of Cp*W(N0)(H)(η³-PhCHCHCHPh) (5.1).Trapping, labelling, and monitoring experiments suggest that 5.1 is formed via 1) the loss of neopentane and the generation of the allene intermediate Cp*W(N0)(η²-CH₂=C=CHPh), 2) the C-H activation of benzene resulting in a phenyl phenylallyl complex, and 3) the thermal isomerization of this latter species to 5.1.

Thermolysis of Cp*W(NO)(CH₂CMe₃)₂ (2.1) in halo, methoxy, or phenylethynyl-substituted benzenes leads to the formation of the alkylidene intermediateCp*W(NO)(=CHCMe₃) which selectively activates ortho C-H bonds of the organicsubstrates. The ortho-regioselectivity diminishes as the size of the substituent increasesfrom F (97 %) to C-=CPh (51 %). In the solid-state structure of all complexes the ortho-substituent is not coordinated to the metal centre; rather, the metal centre is engaged inagostic interactions with a neopentyl methylene C-H bond. Mechanistic studies on the chlorobenzene reaction reveal that the ortho-C-H-activation product is preferentially formed via thermal isomerization from the meta / para-C-H-activation isomers. Reactions between Cp*W(NO)(CH₂EMe₃)Cl (E = C or Si) and a variety of bis(allyl)magnesium reagents lead to the expected formation of Cp*W(NO)(alkyl)(allyl)complexes. Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCH₂) (3.5), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CMeCH₂) (3.6), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7),Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) and Cp*W(N0)(CH₂SiMe₃)(η³-CH₂CHCHMe) (3.9) have thus been synthesized in moderate yields. The solid-state molecular structures of 3.5 and 3.7-3.9 feature a σ-π distorted ally! ligand in the endoconformation. Complex 3.5 reacts with pyrrolidine at RT to form Cp*W(NO)(NC₄H8)(CHMeCH₂NC₄H8) (3.10), a nucleophilic-attack product. Complexes 3.6-3.9 effect the concurrent N-H and α-C-H activation of pyrrolidine at RT and form alkyl-amido complexes analogous to the previously known Cp*W(N0)(CH₂EMe)(NC₄H₇-2-CMe₂CH=CH₂) (3.12). Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7) at RT leads to the loss of neopentane and the formation of the η²-diene intermediate Cp*W(N0)(η²-CH₂=CHCH=CH₂) (A) which has been isolated as a PMe₃ adduct. In the presence of saturated organic substrates, C-H activation occurs exclusively at the methyl positions of the molecule. Reactions between intermediate A and unsaturated substrates lead to coupling between the coordinated η²-diene and the unsaturation on the organic molecule.Treatment of Cp*W(N0)(n-C₅H₁₁)(η³-CH₂CHCHMe) (4.1) with I₂ at -60 °C produces n-C₅H₁₁ I in moderate yields. Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) in benzene at 75 °C for one day leads to the exclusive formation of Cp*W(N0)(H)(η³-PhCHCHCHPh) (5.1).Trapping, labelling, and monitoring experiments suggest that 5.1 is formed via 1) the loss of neopentane and the generation of the allene intermediate Cp*W(N0)(η²-CH₂=C=CHPh), 2) the C-H activation of benzene resulting in a phenyl phenylallyl complex, and 3) the thermal isomerization of this latter species to 5.1. / Science, Faculty of / Chemistry, Department of / Graduate

N-Heterocyclic carbenes (NHCs) are one of the few ligand systems that can finely tune transition metal catalysts via sterics and electronics. The strong sigma-donating properties of these ancillary ligands allow the development of robust tridentate NHC pincer framework, which has emerged as an alternative to the phosphine pincer ligands. The combination of NHC and pincer systems has resulted in a new generation of catalytically active organometallic complexes reported throughout the literature. -NHC Rh pincer complexes were found to be catalytically active in C-C and C-B bond formation via 1,4dition reactions. In addition, the in-situ generated -NHC Ir(H) pincer complex demonstrated catalytic activity in borylation of arene C-H bonds. Preliminary results are comparable to the C-H borylation results published by Hartwig and co-workers. The -NHC Ir(H) pincer complex may also prove to be a suitable catalyst for alkane dehydrogenation, due to framework similarities of the highly active and durable PCP and POCOP pincer hydride systems. Expansion of group 9 metal sources for transmetalation of the -NHC Zr pincer complex afforded the development of -NHC Rh(CO) and -NHC Co complexes. Group 9 metal carbonyl complexes have been reported as active catalysts in photocatalytic C-H activation of small molecules. Testing of Co sources for transmetalation afforded three rare Co pincer complexes, and the first examples of -NHC Co pincer complexes to date. Development of -NHC pincer complexes with base metals provide cost-effect alternatives to pincer systems with precious metal centers, and is reported herein.

Les molécules marquées par des isotopes de l’hydrogène possèdent de nombreuses applications dans divers domaines tels que la chimie, la biologie ou en science des matériaux. Dans le domaine de la recherche de nouveaux médicaments, les études liées à la pharmacocinétique nécessitent un accès rapide à des molécules marquées afin de ne pas impacter les coûts et les délais de développement. Le développement de la métabolomique a aussi entrainé une augmentation du besoin en molécules marquées isotopiquement. En effet, les molécules deuterées peuvent être utilisées en tant qu’étalons internes pour la quantification rapide des métabolites présents dans des tissus ou des fluides biologiques. La première partie de cette thèse concerne le développement d’une méthode générale de marquage de motifs de type thioéther dans des molécules complexes à l’aide d’une nouvelle réaction d’échange isotopique (catalysée par des nanoparticules de Ruthénium). D’un point de vue fondamental cette transformation représente le premier exemple de (Csp³)-H activation dirigée par un atome de soufre. En termes d’application, cette nouvelle réaction permet la synthèse rapide d’étalons internes pour la quantification LC-MS/MS et le marquage tritium de molécules complexes. La seconde partie de cette thèse relate le développement d’une nouvelle méthode d’homocouplage de phénylpyridines catalysée par Ru/C. Différents substrats comportant des substituants riches et pauvres en électron ont été couplés avec de bons rendements. Ces dimères ont ensuite été utilisés pour synthétiser de nouveaux complexes de bore dont les propriétés photophysiques ont été étudiées. Dans une troisième partie, la mise au point d’une réaction palladocatalysée permettant d’obtenir des molécules polycycliques contenant un motif de type pyridine est développée. / Deuterated and tritiated compounds are widely used in numerous applications in chemistry, biology and material science. In the drug discovery and development process, ADME studies require quick access to labelled molecules, otherwise the drug development costs and timeline are significantly impacted. The rapid development of metabolomics has also increased the need for isotopically labelled compounds. In particular, deuterated molecules are used as internal standards for quantitative LC-MS/MS analysis of metabolites in biological fluids and tissues. In this context, a general method allowing the deuterium and tritium labelling of bioactive thioethers using a HIE reaction is described in the first chapter. From a fundamental point of view, this transformation is the first example of (Csp³)-H activation directed by a sulfur atom. In terms of application, this new reaction has been proved to be useful for the preparation of deuterated LC-MS/MS reference materials and tritiated pharmaceuticals owning high specific activity.In the second chapter of this manuscript, the development of a method allowing the cross-dehydrogenative homocoupling of 2-arylpyridines catalyzed by Ru/C is developed. Various substrates with different substituents were efficiently coupled to give the desired dimers in good yield. In terms of application, a series of pyridine-boron complexes derived from the phenyl pyridine dimers were also synthesized and their photophysical properties were studied.In the third chapter, a regioselective palladium catalyzed intramolecular arylation reaction allowing the synthesis of pyridine containing polycyclic compounds is described.