The syntheses of a new class of polycyclic TriAmino DiCarbenes (TADCs), based on 3,9-diazajulolidine, and their precursors and adducts are described. Starting with 2,6-dimethyl-nitrobenzene, 2,6-bis ((alkylamino)methyl)anilines (alkyl = isopropyl, mesityl, and tert-butyl) were synthesized in 40% yield over five steps. These triamines were then di-cyclized stepwise to diformamidinium dications or formamidinium/2-methoxyformaminals using oxonium salts and trialkyl orthoformates. A diformamidinium dication was characterized by single-crystal X-ray diffractometry. Treatment with various bases, particularly lithium hexamethyldisilylazide, led to the novel TADCs and monocarbenes, two of which were isolated and characterized by 1H and 13C NMR spectroscopies. In both cases, treatment with elemental sulfur trapped the TADCs as dithiobiurets. No TADC-transition metal complexes were successfully isolated from reactions of the diformamidinium dications or LiHMDS TADC complex with a number of transition metal complexes. With the exception of these two cases, all other TADCs were not isolated because they rapidly reacted to form dimers, trimers, and tetramers. One of these dimers was isolated and its structure determined using 1D and 2D NMR spectroscopies, along with high-resolution electrospray ionization mass spectrometry. This revealed that the TADC had dimerized to form an ene-triamine, likely via 1,3-shift of a benzylic proton. Novel N-heterocyclic Carbene (NHC) complexes of molybdenum were also synthesized and characterized. Reaction of Cp2Mo2(CO)4 (Cp = C5H5) with dimesityl-imidazol-2-ylidenes (IMes) or dimesityl-imidazolidin-2-ylidenes (SIMes) yielded the molybdoradicals CpMo(CO)2(NHC) (NHC = IMes or SIMes). The carbonyl infrared stretching frequencies and the relative metal-to-NHC π-backbonding for IMes and SIMes complexes are compared. Reaction of the less bulky dimethyl-imidazol-2-ylidene (IMe) with Cp2Mo2(CO)4 yielded the Mo-Mo triple bond complex Cp2Mo2(CO)3(IMe) by CO substitution. This is the first example of an NHC-ligated metal-metal multiply bonded complex. Single crystal X-ray diffractometry of these new organomolybdenum and organodimolybdenum complexes is discussed.

Die Arbeit befasst sich mit der Synthese verschiedener NHC-substituierter Kobaltkomplexe, sowie mit deren Anwendung in verschiedenen Bindungs-Aktivierungsreaktionen und in katalytischen Umsetzungen. / This thesis deals with the synthesis of different NHC-stabilized cobalt complexes as well as with their use in different bond-activation reactions and in catalytic transformations.

Diese Arbeit beschäftigt sich mit Untersuchungen zur Synthese und Reaktivität von Ruthenium(II)- und Eisen(II)-Komplexen welche durch Alkyl-subsituierte N-Heterozyklische-Carben Liganden stabilisiert werden. Ein besonderes Augenmerk liegt hierbei auf dem synthetischen Zugang von Rutheniumverbindungen jenseits der Metathese-Katalysatoren. / This Work is concerned with the inverstigations of the synthesis and reactivity of ruthenium(II) and iron(II) complexes which are sabilised by alkyl-substituted N-heterocyclic carbenes ligands. Particular attention is paid to the synthetic approach towards ruthenium compounds beyond metathesis catalysts.

Die vorliegende Arbeit befasst sich sowohl mit der stöchiometrischen als auch mit der katalytischen Aktivierung von Element-Element-Bindungen an NHC-stabilisierten Nickel(0) Komplexen. / The present work is concerned with investigations of stoichiometric and catalytic element-element bond activation with NHC-stabilized nickel(0) complexes

In der vorliegenden Arbeit wird die Synthese und Reaktivität neuer NHC- und cAAC-stabilisierter Lewis-Säure/Lewis-Base-Addukte von Verbindungen mit Elementen der Gruppen 14 und 15 beschrieben. / This thesis reports on synthesis and reactivity of new NHC- and cAAC-stabilized Lewis-acid/Lewis-base adducts of group 14 and group 15 element compounds.

This dissertation focuses on two different types of organometallic compounds, carbenes and imides. The first project deals with the archetypal Schrock carbene, and the second project studies complexes that contain metal-nitrogen bonds, both amides and imides. A summary of the research in this dissertation is discussed in Chapter 1. Chapter 2 begins the studies of the archetypal Schrock carbene (ButCH2)3Ta=CHBut. The studies include the synthesis of deuterated compounds (ButCD2)3TaCl2 and ButCD2Li, observation and identification of the intermediate, Ta(CD2But)5, and kinetic studies of the conversion of Ta(CD2But)5 to (ButCD2)3Ta=CDBut, giving the activation parameters and a kinetic isotope effect for the conversion. The work here confirms that the pentaneopentyltantalum is the precursor to the archetypal Schrock carbene. Chapter 3 studies the effects of isotopic substitution on NMR chemical shifts of complexes in Chapter 2. Conformations of (ButCD2)3TaCl2 and Ta(CD2But)5 have also been investigated. Chapter 4 begins the study of compounds containing metal-nitrogen bonds. Guanidinate imides Ta(NMe2)(=NSiMe3)[RNC(NMe2)NR]2 (R = Cy, Pri) have been prepared from the reactions of Ta(NMe2)4[N(SiMe3)2] with two equivalents of carbodiimides, RN=C=NR. The two guanidinate imides have been characterized by NMR spectroscopy and elemental analysis. In addition, the structure of Ta(NMe2)(=NSiMe3)[CyNC(NMe2)NCy]2 has been studied by single crystal X-ray diffraction. Under heating, Ta(NMe2)4[N(SiMe3)2] undergoes an unprecedented elimination of Me3Si-NMe2, converting the amide ligand –N(SiMe3)2 to the imide ligand =NSiMe3 to give an intermediate Ta(NMe2)3(=NSiMe3). In the presence of CyN=C=NCy, the carbodiimide captures the intermediate to give another intermediate Ta(NMe2)2(=NSiMe3)[CyNC(NMe2)NCy]. Subsequent second carbodiimide insertion leads to the formation of the final product Ta(NMe2)(=NSiMe3)[CyNC(NMe2)NCy]2. The remaining amide ligand, –NMe2, in Ta(NMe2)(=NSiMe3)[CyNC(NMe2)NCy]2 and Ta(NMe2)(=NSiMe3)[PriNC(NMe2)NPri]2 gives two separate resonances in the proton NMR spectrum at room temperature indicating inequivalence of the two methyl groups. The interconversion of the methyl groups in the former has been studied with variable-temperature NMR. Chapter 5 studies the synthesis and characterization of metal cage complexes [(Me2N)3MO]4 (M = Nb, Ta). Single crystal X-ray diffraction studies show a cubane-like structure with M-O bridges. Variable-temperature NMR of the inequivalent amide methyl groups –NMeAMeB has also been carried out to find the activation parameters for the exchange.

Several new late transition metal complexes containing P-O and P-N ligands derived from 2-dicyclohexylphosphinoacetaldehyde were synthesized. A facile one-pot template method is used for the synthesis of P-N complexes, where the phosphine aldehyde and amine can undergo a condensation reaction to form a phosphine-imine metal complex in the presence of a metal precursor. Metal complexes with phosphino-enolate, imine, and oxime ligands are synthesized. Ni(II), Pt(II), Rh(I) and Ir(I) metal centres were investigated. The Rh(I) and Ir(I) complexes contain a 1,5-cyclooctadiene ligand, thus resembling Crabtree’s hydrogenation catalyst [Ir(COD)(py)(PCy3)][PF6]. These complexes are also active catalysts for olefin hydrogenation. Furthermore, the synthesis of a new chiral amine functionalized NHC ligand is explored, which has potential applications as a ligand in the metal-catalyzed enantioselective hydrogenation of polar bonds. This ligand is inspired by previous achiral hydrogenation catalysts reported by Morris et al. that displayed high activity for a variety of unsaturated substrates.

In recent years, N-hetereocyclic carbenes (NHCs) have received considerable attention as organocatalysts due to their unusual ability to induce a reversal of reactivity (Umpolung) in aldehydes. Indeed, NHCs unique properties have been applied to the efficient and metal-free synthesis of organic compounds that have proven elusive using traditional approaches.<p> My Masters research program has been focused on the use of NHCs as organocatalysts in ring expansion reactions and their applications to cascade reactions.<p> During my Masters studies, an NHC-catalyzed efficient ring expansion of 4-, 5-, and 6-membered oxacycloalkane-2-carboxaldehydes to generate the corresponding lactone derivatives was developed. This reaction provides access to a variety of lactones using readily available NHCs under mild conditions.<p> Then, the ring-expansion lactonization has been successfully extended to an efficient lactamization using azacycloalkane-carboxaldehydes, which could provide functionalized lactams in moderate yields under mild conditions.<p> In addition, intrigued by the possibility of effecting the Umpolung of electron-poor dienes using NHC catalysts, the ring-expansion lactonization was applied to an attempted Diels-Alder-ring expansion cascade reaction. Though no cascade reactions were observed, some very interesting results were obtained, and those results will guide future investigations in this area.

L'objectif de la thèse était la préparation et la caractérisation des catalyseurs hétérogènes à base de polyoxométalates. L'étude mécanistique d'oxydation du méthane jusqu'au méthanol a montré que sur des polyoxométalates supportés sur la silice l'activation C-H a lieu déjà à la température ambiante. L'adsorption du méthane-13C sur H4SiMo12O40 supporté, suivie par RMN solide a mis en évidence la création de l'espèce méthoxy [SiMo12O40(CH3)]3-. Le cycle catalytique est complété par l'hydrolyse de cette espèce - méthanol est formé et une molécule de l'eau recrée la structure du départ de polyoxométalate. L'adsorption du méthanol-13C sur des polyoxométalates a montré la création de deux types des espèces methoxy, localisées sur des atomes d'oxygènes terminaux ou pontants est caractérisées par deux signaux RMN distincts - à 58 et 77 ppm, respectivement. En greffant un complexe de platine PtMe2COD sur les sels de césium de polyoxometalates, le dégagement du méthane ou de la mélange du méthane et de l'éthane a été observé et expliqué par la séquence de l'addition oxydative du proton de polyoxometalate au centre métallique, couplage C-H ou C-C et finalement l'élimination réductrice et libération d'une molécule de gaz. Sels d'ammonium de l'acide phosphotungstique H3PW12O40 ont été montrées de catalyser l'isomérisation du n-butane a l'isobutane dans des conditions douces (225°C, 1 atm.). Composé du cuivre Cu(OTf)2 sur la surface des sels inorganiques des polyoxometalates donne des catalyseurs très actifs en insertion des carbènes aux liaisons C-H des éthers cycliques.

In recent years, N-hetereocyclic carbenes (NHCs) have received considerable attention as organocatalysts due to their unusual ability to induce a reversal of reactivity (Umpolung) in aldehydes. Indeed, NHCs unique properties have been applied to the efficient and metal-free synthesis of organic compounds that have proven elusive using traditional approaches.<p> My Masters research program has been focused on the use of NHCs as organocatalysts in ring expansion reactions and their applications to cascade reactions.<p> During my Masters studies, an NHC-catalyzed efficient ring expansion of 4-, 5-, and 6-membered oxacycloalkane-2-carboxaldehydes to generate the corresponding lactone derivatives was developed. This reaction provides access to a variety of lactones using readily available NHCs under mild conditions.<p> Then, the ring-expansion lactonization has been successfully extended to an efficient lactamization using azacycloalkane-carboxaldehydes, which could provide functionalized lactams in moderate yields under mild conditions.<p> In addition, intrigued by the possibility of effecting the Umpolung of electron-poor dienes using NHC catalysts, the ring-expansion lactonization was applied to an attempted Diels-Alder-ring expansion cascade reaction. Though no cascade reactions were observed, some very interesting results were obtained, and those results will guide future investigations in this area.