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1
Fout, Alison R. "Unraveling strong bonds small molecule activation via metal-ligand multiple bonds /." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3344762.
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Thesis (Ph.D.)--Indiana University, Dept. of Chemistry, 2009.Title from PDF t.p. (viewed on Oct. 8, 2009). Source: Dissertation Abstracts International, Volume: 70-02, Section: B, page: 1015. Adviser: Daniel J. Mindiola.
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Rene, Olivier. "Advances in Palladium-Catalyzed Carbon-Carbon Bond Formation Via Functionalization of Carbon-Hydrogen Bonds." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28864.
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In the past decade, significant advances have been made in the formation of Csp2-Csp 2 bonds by direct arylation. However, this process generally requires the use of forcing conditions at temperatures typically above 100 °C, which limits the substrate compatibility as well as large-scale applications. Inspired by the recent advances in the development of milder reaction conditions for the arylation of electon-rich arenes in an aqueous medium, we describe that such reactivity is also possible with electron-deficient polyfluorinated arenes at room temperature under biphasic conditions. Several examples are included, highlighting the application of this method to the preparation of a variety of biaryls using iodides bearing electron-poor, electron-rich and sterically encumbering substituents. Several polyfluoroarenes with different substitution patterns are also tolerated. In addition, the method can be extended to the arylation of halogenated thiophenes in a regioselective fashion.
However, direct arylation conditions that are general for a broad variety of heterocyclic coupling partners are only sparsely reported and the use of a different set of conditions for each type of substrate remains the norm. As part of a program dedicated to the study of the direct arylation mechanism and the development of broadly applicable reaction conditions, we became interested in investigating the effect of electron-deficient biaryl-type phosphine ligands on the C-H bond cleavage step of this process under Pd(0) catalysis. Inspired by previous reports validating the efficiency of these types of ligands in intramomecular direct arylation, we have developed a new electron-deficient fluoroarylphosphine ligand that promotes C-H bond functionalization of a broad variety of heterocycles. The demonstrated ability of these types of ligands to facilitate the C-H bond cleavage step of this process has been assessed and experimental evidence suggests a concerted metalation-deprotonation mechanism in the presence of an electrophilic metal center.
Only recently, nonetheless, has attention been paid to the formation of Csp3-Csp2 bonds by the direct arylation strategy. As an alternative to the use of aliphatic halides as an entry point to a1kylpalladium(II) intermediates, we describe the use of a Heck-like cyclization of an aryl halide as a means of intercepting the key palladium(II) species, along with the first examples of domino Heck-arylation involving intermolecular capture with heterocyclic arenes via C-H bond cleavage. Several examples are presented, demonstrating the application of this method to the preparation of diverse dihydrobenzofurans, indolines and oxindoles substituted with sulfur-containing heterocycles such as thiazoles, thiophenes and benzothiophene.
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Correia, Camille. "Oxidative C-C bond formation via metal-catalyzed coupling of two C-H bonds." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114441.
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This thesis describes the formation of new C-C bonds from the direct oxidative coupling of two C-H bonds, through the use of metal catalysts for activation. First, three different oxidative Cross-Dehydrogenative-Coupling (CDC) reactions will be presented. Initially, through the use of an organic co-catalyst, N-hydroxyphthalimide (NHPI), oxygen could be utilized as the terminal oxidant for the metal catalyzed alkylation of benzylic C-H bonds with 1,3-dicarbonyls and ketones in Chapter 2. The reaction was found to be feasible for a variety of substrates with readily enolizable C-H bonds. Next, the 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) mediated alkynylation of sp3 C-H bonds was studied. A novel copper (I) triflate catalyzed CDC reaction of unactivated benzylic C-H bonds and terminal aromatic alkynes is presented in Chapter 3. After further studies, the alkynylation of benzylic ethers could also be realized in the presence of a catalytic amount of silver (I) triflate, as described in Chapter 4. Both procedures were found to be amendable for aromatic terminal alkynes, however could not be extended to aliphatic alkynes. Finally, a palladium catalyzed Minisci-type reaction will be described in Chapter 6. Peroxide generated α-hydroxyalkyl radicals could be reacted with azines in moderate to good yields. A stoichiometric amount of acid, used in the traditional Minisci reaction, was replaced by a catalytic amount of palladium dichloride.Cette thèse décrit la formation de nouvelles liaisons C-C par activation oxydative directe de deux liaisons C-H grâce à l'utilisation de métaux de transition comme catalyseurs. La première partie présentera trois différentes réactions de Cross-Dehydrogenative-Coupling (CDC) oxydantes. Dans un premier temps, sera présentée dans le chapitre 2, la réaction d'alkylation de liens C-H benzylique par 1,3-dicarbonyles et cétones. Ce system a démontré son efficacité sur une large variété de substrats contenant des liaisons C-H enolysable. De plus il a été rendu possible, grâce à l'utilisation d'un co-catalyseur organique, le N-Hydroxyphthalimide (NHPI), d'utiliser l'oxygène moléculaire comme oxydant terminal. Dans un second temps, nous étudierons l'utilisation du 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) comme médiateur pour l'alkynylation de liaisons sp3 C-H. Une nouvelle CDC réaction catalysée par le triflate de cuivre (I) sera présentée dans le chapitre 3, entre un alcyne et une liaison C-H benzylique. Le chapitre 4 présentera le développement de cette réaction à l'alcynation d'éthers benzyliques en présence d'une quantité catalytique de triflate d'argent (I). Ces deux procédures sont seulement applicables pour les alcynes vrais aromatiques. Finalement, le chapitre 6 portera sur la réaction de Minisci catalysée par le palladium. Le peroxyde radical α-hydroxyalkyl généré lors de la réaction est capable de réagir avec les azines. La quantité stœchiométrique d'acide nécessaire lors de la traditionnelle réaction de Minisci, a été remplacée par une quantité catalytique de dichloro palladium.
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Walton, Scarlett Maria. "Catalytic functionalisation of sp3 bonds." Thesis, University of Huddersfield, 2017. http://eprints.hud.ac.uk/id/eprint/34344/.
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Reported herein is an investigation into palladium-catalysed -allylation employing sulfonamide nucleophiles. Anions of benzylsulfonamides have been shown to react with a series of allyl acetates in the presence of Pd0 catalysts, phosphine ligands and base at room temperature, enabling the synthesis of sp3-functionalised sulfonamides. The developed methodology has allowed access to a library of novel allylated sulfonamides, varying both amine substituent and allylic functionality. In addition, we have applied our methodology to a series of known sulfonamide drug targets, to demonstrate our reaction as a useful late-stage functionalisation tool, whilst populating chemical space. The performed mechanistic study using a stereospecific electrophile confirms benzylsulfonamides behave as soft carbon nucleophiles in the Tsuji-Trost reaction, as a ‘net retention’ of stereochemistry is observed (confirmed by X-ray crystallography). Moreover, the asymmetric synthesis of allylated sulfonamides is probed, although obtaining enantioselectivity a- to SO bonds is naturally difficult, due to the conformational preferences of sulfonamide carbanions. Traditional methods for direct -alkylation of sulfonamides require strong bases, reactive electrophiles, low temperatures and use of stoichiometric amounts of additives. Therefore, in addition to a catalytic method, we report an alternative method reacting benzylsulfonamides with allyl bromide electrophiles via a nucleophilic substitution reaction, using mild conditions (LDA, THF at –20 °C).
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English, Jason B. "Electronic structure investigations of multiple bonding between atoms: From metal-nitrogen triple bonds to metal-metal triple and quadruple bonds." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280021.
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The nature of multiple bonding involving transition metal atoms has been explored via photoelectron spectroscopic and computational studies of molecules containing metal-metal quadruple and triple bonds as well as of molecules containing formal metal-nitrogen triple bonds. The principles governing the nature of the multiple bonding in these systems are similar whether the multiple bonding occurs between two transition metals or between a transition metal and a nitrogen atom. First, the electronic structures of the R₃M≡N molecules, where R = ᵗBuO (Cr, Mo, W); iPrO (Mo); (CH₃)₂CF₃CO (Mo); and Cl (Mo), are examined by photoelectron spectroscopy in conjunction with density functional calculations. To assign the features seen in the photoelectron spectra, close attention is paid to the effects of (1) metal substitution and (2) alkoxide (or Cl) substitution. Examination of the photoelectron spectra of the full series of alkoxide-substituted molecules allows the relative positions of the ionizations from the M≡N σ and π orbitals to be identified. Of great importance to the electronic structure of these molecules are the alkoxide orbital combinations that mix strongly with the M≡N σ and π orbitals. The importance of the ancillary ligand combinations is clearly demonstrated by the photoelectron spectroscopic and computational studies of Cl₃Mo≡N. The replacement of the alkoxide ligand with chlorides greatly simplifies the resultant photoelectron spectrum, allowing all of the valence ionizations to be assigned. Next, the bonding in the M₂X₄(PMe₃)₄ molecules, where M = Mo (X = Cl, Br); W (X = Cl); and Re (X = Cl, Br, I), is explored by photoelectron spectroscopic investigations in conjunction with electronic structure calculations. From these investigations, the ionizations from the metal-based orbitals as well as several ligand-based orbitals have been assigned. The first ionization energies of both the molybdenum (δ) and rhenium (δ*) molecules decrease as the electronegativity of the halide increases. The origin of this inverse halide effect is explored. Finally, the nature of the quadruple metal-metal bond in the M₂(chp)₄ molecules (M = Cr, Mo, W; chp = 2-chloro-6-oxo-pyridinate) is probed. For all three metal systems, an ionization from the M₂ δ orbital can be seen. This is only the second time a distinct ionization feature has been noted for ionization of the delta orbital from a dichromium molecule. Comparisons with the previously studied M₂(mhp)₄ molecules (mhp = 6-methyl-2-oxo-pyridinate) allow for a better understanding of the electronic structure of these molecules.
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Hare, P. M. "Studies concerning carbon-hydrogen-metal bonds." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370264.
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Kelly, Eugene John. "Catalytic activation of carbon-hydrogen bonds." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333819.
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Welideniya, Dhanushi Thathsara. "Supramolecular chemistry of small molecular fundamentals to drug–receptor applications." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19106.
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Doctor of PhilosophyDepartment of Chemistry
Christer B. Aakeroy
A family of bis-pyridine based pharmaceutical active ingredients were synthesized and co-crystallized with four iodoperfluoroalkanes. Thirteen new crystal structures that are driven by I‧‧‧N(py) halogen bonds, are presented and compared with that of their hydrogen-bonded analogues. Halogen bonded co-crystals exhibit two different structural arrangements, as opposed to layered architectures observed in hydrogen bonded co-crystals. In order to explore the effect of aromatic stacking interactions on hydrogen and halogen bond driven co-crystallization process, we utilized a series of aromatic hydrogen and halogen bond donors in combination with bis-pyridine based pharmaceutical active ingredients. Aromatic stacking between the donor and the acceptor were limited, due to the lack of complementarity between the donor and the acceptor in terms of size, shape and geometry. In that case, homomeric interactions between the single components were translated into the structure of the binary co-crystals. According to our charge calculations, similarly activated hydrogen and iodine atoms possess similar electrostatics. Therefore, we wanted to investigate the interchangeability of hydrogen bonds and halogen bonds by utilizing 2-aminopyrimidine as the backbone for C(sp)-H and C(sp)-I functionalities which makes self-complementary ribbons via NH‧‧‧N synthons. Our results show that the ethynyl proton is capable of acting as a synthon mimic of ethynyl iodine by interchangeable C(sp)-H‧‧‧N hydrogen bonds and C(sp)-I‧‧‧N halogen bonds. We exploited the halogen bonding donor capability of iodo, bromo and chloro ethynyl functionalities towards a series of halide ions. Based on the grinding experiments these donors showed 90%, 70% and 50% success rates towards halides. Among the halides, chlorides exhibited the highest red shift compared to bromides and iodides. We synthesized a series of cavitands functionalized with hydrogen bond donor and acceptor groups and studied their binding preferences towards a series of active ingredients. We have shown that suitably functionalized cavitands can act as carriers of active ingredients and especially, selective binding of aspirin is demonstrated using a two-point binding mode.
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Bencivenga, Nicholas Ernest. "Enantioselective nickel catalysis : exploiting activated C-H bonds." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/73437.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 26-27).
A method for the nickel-catalyzed cross-coupling between benzoxazole and secondary halides was explored. This method was to make use of the activated C-H bond found in benzoxazole at the 2-position to generate the nucleophilic species in situ. After an extensive survey of parameters no such method could be found. However, it was found that copper(I) salts promoted the coupling of benzoxazole and benzylic bromides in high yield, albeit in a racemic fashion. Additionally a method to cross-couple terminal alkynes with secondary halides employing nickel-catalysis was explored. After surveying a number of alkynylmetal species, generated in situ, alkynyl borates were found to cross-couple with allylic chlorides to furnish product with the best enantioselectivity (enantiomeric excess ca. 70%), however in low yield.
by Nicholas Ernest Bencivenga.
S.M.
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Hugas, Germà David. "Dihydrogen bonds: a study." Doctoral thesis, Universitat de Girona, 2010. http://hdl.handle.net/10803/7945.
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Un pont de dihidrogen (dihydrogen bond,DHB) és un tipus de pont d'hidrogen atípic que s'estableix entre un hidrur metàl·lic i un donador de protons com un grup OH o NH. Els ponts de dihidrogen són claus en les característiques geomètriques i altres propietats de compostos que en presenten tan de molècules petites com el dímer de NH3BH3, com d'estructures superiors més complicades com complexes metàl·lics o sòlids. Poden ser útils aplicats a certes molècules o síntesis moleculars per a obtenir nous materials amb propietats o característiques fetes a mida. El treball d'aquesta tesi està orientat a millorar la comprensió dels ponts de dihidrogen, aprofundint en certs aspectes de la seva naturalesa atòmica/molecular utilitzant mètodes teòrics basats en la química física quàntica.A dihydrogen bond (or DHB) is a kind of unconventional hydrogen bond, established between a metal hydride bond and a proton donor like OH or NH. They are the key to important structure features and properties in compounds which have them. They can be responsible for the specific geometry not only of small molecules like the NH3 BH3 dimer, but also of higher structures like metallic complexes or solids. It is in this fashion that dihydrogen bonds can be profitable, up to a plausible extent, when they can be used in certain molecules or certain syntheses to obtain a new material with particular or even tailored properties or geometries. The work developed in this thesis is aimed to have a deeper understanding of dihydorgen bonds, deepening on certain aspects using theoretical methods.
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Fried, Stephen D. (Stephen David) 1987. "Oxygen-oxygen bonds : catalytic redox pathways in energy storage." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49754.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.Vita.
Includes bibliographical references.
Introduction: The present understanding of energy - its many forms, and its governing role in the time evolution of physical systems - underlies many of the most fundamental and unifying principles furnished by scientific theories. We are now deeply aware that energy is inherently quantized and is associated with stationary states (from quantum theory), that it is conserved (from the first law of thermodynamics), but that its conversion is asymmetric and not invariant to time reversal (from the second law of thermodynamics). The transaction of energy from one system to another system; from one form to another form, is deeply embedded in our interpretation of Nature, and refining what precisely energy is tells a large portion of the story that is Science. In contrast, energy technologies allow mankind to harvest (by converting the form of) natural "banks" of energy - primarily the chemical bonding energy of organic molecules in reduced states - in order to perform tasks to our liking: there are many such tasks, but a significant portion of them involves the transformation into electricity. It is certain that one of the most significant challenges facing developed society in the 21st century will be devising how to derive energy in the form of electricity in large quantities from sources other than fossil fuels. Because fossil fuels have been used so monolithically, new methods of providing useful energy without them have gone undeveloped until only the last few decades. A large number of efforts in scientific research from a panoply of disciplines today are motivated by this challenge. There are many ways of addressing such a far-reaching problem, but one attractive and thoughtful strategy to probe it is to consider by what means all the chemical energy that has been harvested from fuels since the Industrial Revolution was "made" in the first place. Essentially all terrestrial banks of energy are derived originally from solar radiation, and the development of the photosynthetic process by cyanobacteria some 3.5 billion years ago,1 which (in general terms) couples light energy to drive endothermic electron transfer reactions, is perhaps the most significant development in geological history. However, how this solar energy is actually used and stored in nature is intimately tied to the chemical bond between two oxygen atoms. The common theme that ties my research projects in the Nocera group in the past four years is an interest in systems that transfer energy through the making and breaking of oxygen-oxygen bonds. 0-0 bonds are some of the weakest covalent bonds in nature, with bond dissociation enthalpy (BDE) values near 33 kcal mol-1 in H202 . By simple thermodynamic arguments, the formation of these bonds from energy-rich O-H and C=O bonds is uphill, and the consumption of these bonds in reactions that oxidize other reagents are exothermic, and if not carefully controlled, explosive. Indeed Nature decided to employ the free energy liberated by the reduction of molecular 02 to obtain the vast majority of energy available to aerobic heterotrophic organisms via respiration. Presently, the highly active area of fuel cell technology is tied intrinsically to a question that cells had to answer long ago in evolutionary history: how does one maximize an output potential (i.e., minimize the overpotential) generated by the reduction of 02 with H2 as reductant 2 Nature's own fuel cell, cytochrome c oxidase (CcO), evolved to drive the complete reduction of 02 by an "H2 equivalent" in the form of NADH (the reduced form of nicotinamide adenine dinucleotide), which is exothermic by 1.229 electron volts (eV) per elementary charge transferred as shown on the left side of Scheme 1. An incomplete reduction of 02 leads to the formation of hydrogen peroxide (H2O2) ...
by Stephen D. Fried.
S.B.
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Brain, Paul Terence. "Studies of some compounds containing boron-boron bonds." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291091.
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O'Hare, D. M. "Activation of carbon hydrogen bonds by metal atoms." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355789.
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Sau, Roca Míriam. "From Click Chemistry to catalytic cleavage of unstrained C-C bonds." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396080.
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Aquesta tesi doctoral es basa principalment amb la síntesis de molècules petites potencialment útils per investigacions avançades. S'han utilitzat diferents metodologies per obtenir-les:
1) Cicloaddicions intramoleculars entre un alkí i una azida lliures de coure per l'obtenció de derivats de benzodiazepines. Obtenint-se una gran varietat de triazols fusionats a heterocicles de set membres. Posteriorment, s'han dut a terme proves d'activitat biològica.
2) a) Trencament d'enllaços carboni-carboni no activats d'amino alcohols i utilització d'aquest com a nucleòfil juntament amb bromurs d'aril en una reacció d'acoplament catalitzada per pal.ladi per l'obtenció de dibenzil amines. S'ha dut a terme una gran optimització dels diferents paràmetres de reacció; base, dissolvent, electròfil, temperatura, catalitzador i lligand.
b) Trencament d'enllaços carboni-carboni no activats de N-alil amino alcohols i utilització d'aquest com a nucleòfil juntament amb bromurs d'aril en una reacció d'acoplament catalitzada per pal.ladi per l'obtenció d'aldehids arilats en la posició beta. S'ha dut a terme la síntesis d'un gran nombre d' amino alcohols nous i aquests han estat sotmesos a les condicions optimitzades de reacció. Demostrant que aquest transformació és útil per un gran ventall de substrats (bromurs d'aril i amino alcohols).L'enamina resultant de la reacció d'acoplament s'ha aconseguit alquilar amb vinil metil cetona amb bons rendiments però pobres diastereoselectivitats tot i així s'ha demostrant que la reacció és factible. Per finalitzar, s'ha aconseguit desenvolupar la versió enantioselectiva de l’anterior transformació obtenint bons excessos enantiomerics tot i que baixos rendiments.Ésta tesis doctoral está basada principalmente en la síntesis de moléculas pequeñas potencialmente útiles para investigaciones avanzadas. Se han empleado diferentes metodologías para obtenerlas: 1) Cicloadiciones intramoleculares entre un alkino y una azida libres de cobre para la obtención de derivados de benzodiazepinas. Se han obtenido una gran variedad de triazoles fusionados a heterociclos de siete miembros. Posteriormente se han realizado pruebas de actividad biológica de las moléculas resultantes. 2) a) Escisión de enlaces carbono-carbono no activados de amino alcoholes y utilitzación de éstos como nucleófilos conjuntamente con bromuros de arilo para una reacción de acoplamiento catalizada por paladio para la obtención de derivados de dibenzil aminas. Se ha realizado una gran optimización de las condiciones de reacción; base, disolvente, electrófilo, temperatura, catalizador y ligando. b) Escisión de enlaces carbono-carbono no activados de N-alilo amino alcoholes y la utilización de éste como nucleófilo conjuntamente con bromuros de arilo en una reacción de acoplamiento catalizada por paladio para la obtención de aldehídos arilados en posición beta. Se ha realizado la síntesis de un gran numero de amino alcoholes nuevos y éstos se han sometido a las condiciones optimizadas de reacción. Demostrando que ésta transformación es útil para una gran variedad de sustratos (bromuros de arilo y amino alcoholes). La enamina resultante de la reacción de acoplamiento se ha alquilado con vinil metil cetona con buenos rendimientos pero pobres diastereoselectividades aunque se ha demostrado que la reacción es factible. Para finalizar, se ha desarrollado la versión enantioselectiva de la anterior transformación obteniendo buenos excesos enantioméricos aunque con bajos rendimientos.
This PhD thesis is based basically on synthesis of small molecules potentially useful for further investigations. Different strategies have been used to obtain them; 1) Copper free intramolecular cycloadditions between an azide and an akyne for the obtention of benzodiazepine derivatives. A wide range of triazoles fused to seven membered heterocycles rings have been obtained. Later, biological studies have been carried out. 2)a) Carbon-carbon bond cleavage of amino alcohols has been carried out with the subsequent use of them as a nucleophile together with aryl bromides to develop a cross-coupling reaction for the obtention of dibenzyl amines. A wide optimization of the reaction parameters was carried out; base, ligand, catalyst, electrophile, temperatura, and solent. b) Carbon-carbon bond cleavage of N- allyl amino alcohols has been carried out with the subsequent use of them as a nucleophile together with aryl bromides to develop a cross-coupling reaction for the obtention of beta arylated aldehydes. An important number of new amino alcohols have been synthesized and these have been subjected to the optimized reaction conditions. It has been demonstrated that this transformation is useful for a wide range of substrates (amino alcohols and aryl bromides). The resultant enamine has been alkylated with methyl vinyl ketone with good yields but poor diastereoselectivity. To finish the enantioselective version of beta functionalization of aldehydes has been developed obtaining good enantioselectivity but poor yields
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Dombrowski, James Michael. "Catalytic Cleavage of Carbon-Carbon Sigma Bonds Using Transition Metals." Thesis, Boston College, 2005. http://hdl.handle.net/2345/407.
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Thesis advisor: Lawrence T. ScottThe focus of this project was to probe the ability of various transition metal complexes to cleave carbon-carbon bonds in a C30H12 hemifullerene. The hemifullerene was synthesized in our lab from commercial 1-tetralone and bromonaphthalene in six steps. Palladium and nickel complexes were used to open the five membered rings along the periphery of the C30H12 bowl. Diphosphine complexes of nickel were capable of opening either all three five membered rings or one of the periphery five membered rings and the central six membered ring
Thesis (BS) — Boston College, 2005
Submitted to: Boston College. College of Arts and Sciences
Discipline: Chemistry
Discipline: College Honors Program
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Stenhagen, Ida Sofia Refsholt. "New methods for the construction of C-18F bonds." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:871a7e8c-a4d3-4acb-a25d-5946dec2f44d.
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The main electrophilic source used in radiolabelling is [18F]F2, which is highly reactive, toxic and requires specialist equipment for safe handling. The Gouverneur group has initiated a research programme focused on the preparation of new stable and easy-to-handle N-18F reagents. In the development of [18F]radiolabelling reactions it would be extremely valuable to develop a library of selective N-18F reagents possessing reactivity tailored to the desired chemical transformation. The aim of this thesis is to further assess the scope of electrophilic N- 18F reagents in new transformations for the construction of C-18F bonds.
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Stafford, Carolyne. "The sequential insertion of carbon monoxide and imines into nickel-carbon sigma-bonds and kinetic analysis of imine insertion into palladium-acyl sigma-bonds." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18447.
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ABSTRACT The Sequential Insertion of Carbon Monoxide and Imines into Nickel-Carbon Sigma-Bonds and Kinetic Analysis of Imine Insertion into Palladium-Acyl Sigma-Bonds The coupling of imines and carbon monoxide mediated by late transition metals has been previously reported in the Arndtsen laboratory. The fundamental properties of 2,1-migratory insertion of imines into nickel- and palladium-acyl bonds are presented in this text. This study investigates the use of neutral eta2-N,O-salicylaldiminato nickel (II) systems (Chapter 2) as potential complexes to mediate the sequential insertion of carbon monoxide and imines. These complexes undergo rapid carbon monoxide insertion. Subsequent imine insertion is permitted when the imine substrate is sterically unencumbered. The coupling product disproportionates leading to the formation of 1,2-diamides. In our laboratory, kinetic and thermodynamic studies on the coordination and 2,1-migratory insertion of imines into palladium-carbon sigma-bonds were the focus of former student Rania Dghaym, Ph.D. Chapter 3 completes these studies, and offers a mechanistic picture of the pathway by which 2,1-migratory insertion into palladium-acyl bonds proceeds. Our mechanistic data suggest that imine insertion is distinct from olefin insertion and involves the concerted migratory attack of the sigma-coordinated imine to the electrophilic acyl ligand.RÉSUMÉ L'insertion séquentielle de monoxyde de carbone et d'imines dans des liens sigma nickel-carbone ainsi que l'analyse cinétique de l'insertion d'imines dans le lien palladium-acétyle Le couplage d'imines et de monoxyde de carbone médié par des métaux de transition a été récemment publié par le laboratoire du Professeur Arndtsen. Les propriétés fondamentales de l'insertion migratoire-2,1 d'imines dans les liens nickel- et palladium-acétyle sont présentées dans le texte ci-présent. Les complexes neutres eta2-N,O-salicylaldiminato de nickel (II) sont le sujet de recherche dans le chapitre 2 pour leur potentiel de médier l'insertion séquentielle de monoxyde de carbone et d'imine. L'insertion de monoxyde de carbone dans le lien nickel-méthyle est rapide. Par contre, l'insertion d'imine subséquente est seulement observée dans les cas où l'encombrement stérique de celle-ci est minime. Le produit du couplage mène à la formation de 1,2-diamides. Dans notre laboratoire, la cinétique et thermodynamique de l'insertion migratoire-2,1 dans les liens sigma palladium-carbone était le sujet d'étude de Rania Dghaym, Ph.D., une étudiante précédente du laboratoire. Au chapitre 3 nous présentons la suite de ses études et offrons un portrait global du mécanisme par lequel l'insertion migratoire-2,1 dans les liens palladium-acétyle se produit. Nos résultats suggèrent que le mécanisme d'insertion d'imines est distinct de celui d'insertion d'oléfines et implique une attaque migratoire concertée de l'imine sigma-coordonnée au ligand acétyle électrophilique.
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Da, Cruz Ana Cristina Fernandes. "C-H bonds as functional groups for palladium catalysis." Thesis, University of Bath, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.586169.
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Robertson, A. H. Jean. "Properties of CH bonds in alkyl transition metal compounds." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241468.
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This Thesis describes the results of a detailed vibrational study of a representative series of methyl and ethyl derivatives of transition metals. The primary objective of the work was to show that vibrational frequency data can be used to provide information on CH bond lengths, HCH angles and alkyl group geometries with an accuracy and reliability which is not readily attainable by other methods, and that the vibrational technique is generally applicable to a wide variety of organometallic compounds. The work involved the preparation of protonated, partially deuterated and fully deuterated examples of the molecules studied and made particular use of correlations between 'isolated' CH stretching frequencies, v15CH, measured in partially deuterated systems, and CH bond length and HCH angles. In the case of MeM(CO)2Cp (M = Fe,Ru), it is shown that, unlike related molecules of this type, the results show no evidence for a high barrier to internal rotation of the methyl group. The titanium compound MeTiCl2Cp, is shown to be non-agnostic, with the only unusual feature being an unusually low δ5CH3 frequency. In the ethyl series preliminary studies necessitated a careful re-examination of the accepted assignments for ethyl halides, leading to changes in some cases. Following this, detailed assignments are made, wherever possible, for the ethyl metal compounds, with particular emphasis on the CH stretching region. In all of the ethyl metal compounds, the α and β-CH bonds are considerably longer, and weaker, than those in the ethyl halides, and the terminal methyl group invariably contains two dissimilar types of CH bond, differing in the CH stretching frequency by as much as 58cm-1. The longer CH bonds in these ethyl compounds are trans to the metal atoms and are amongst the weakest to have been identified in alkyl metal systems.
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McKay, Findlay J. "Properties of CH bonds in inorganic and isopropyl esters." Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274800.
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The work described in this thesis sets out the results of a vibrational study on a series of methyl and isopropyl sulfate, selenate and phosphate esters, based on a detailed analysis of the infrared spectra of an extended series of deuterated and partially deuterated isotopomers of the compounds of interest. Due to difficulties intrinsic to the analytical method it was important to develop a synthetic method that would be equally applicable to all the inorganic esters studied. The use of a transmetalation reaction, followed by addition of the required isotopically substituted alkyl halide allowed all isotopomers to be easily produced and analysed. A detailed analysis of the infrared spectra was carried out for all isotopomers prepared with particular emphasis on the vibrations associated with the alkyl groups. This allowed, where possible, the accurate assignment of peaks to fundamental, overtone or combination modes. Using the information gained along with well-established relationships between CH bond properties and the experimentally observed isolated CH stretching frequency, visCH, it was possible to calculate CH bond lengths, bond dissociation energies and where applicable HCH bond angles. The use of visCD instead of visCD as an alternative predictor of CH bond properties was also investigated. The results showed clearly that bond properties derived from visCD data are subject to a much greater degree of uncertainty than those obtained from visCH.
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Wilkinson, A. "Catalytic activity of complexes containing weak metal-ligand bonds." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376114.
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Jang, Nak Han. "Developing and validating a chemical bonding instrument for Korean high school students /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3115557.
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Freundlich, Joel Stephen. "Metal-ligand multiple bonds in organometallic complexes containing triamidoamine ligand systems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38782.
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Hamilton, Craig D. "Density functional calculations of organometallic complexes containing metal-metal multiple bonds /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487950153600457.
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Inami, Tasuku. "Studies on Nickel-Catalyzed Reactions via Alkyne Insertion into Carbon-Sulfur Bonds." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199274.
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Lynn, Matthew Allen. "Metal, ligand, and symmetry influences on metal-metal bonds: Photoelectron spectroscopy and theory." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284089.
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Three sets of metal-metal bonded systems of the form M₂(L ͡ L)₄ have been studied by gas-phase ultraviolet photoelectron spectroscopy and electronic structure calculations to understand the electronic structures of and bonding in these molecules. The ligand sets range from the relatively poor electron donor trifluoroacetate ligand, to hydroxymethylpyridinate (mhp), and finally to the relatively strong electron donor N,N'-diphenylformamidinate (form) ligand. Not only does this study elucidate the methods by which metal and ligand interact throughout a series of differing electron donor ligand sets, but it also presents a cohesive understanding of the electronic structures of these systems in terms of overall molecular symmetry. In particular, the relative stabilities and orbital characters of the metal-metal bonding and antibonding orbitals are probed to understand the ability of a particular ligand set to affect the ability of two metal atoms to bind together. First, compounds of the form M₂(form)₄ (M = Cr, Mo, W, Ru, Rh, Pd) are examined. The spectra of the metal-metal quadruple bond-containing systems (i.e., M₂(form)₄ where M = Cr, Mo, W) are used to identify several metal- and ligand-based ionization features, which can then be used to identify the additional metal-based features in the spectra of the remaining systems. Given the ease with which functional groups can be added to the formamidinate ligand, a series of substituted Mo₂(form)₄ systems have been prepared and their ionization data have been compared with solution-phase electrochemical results. Next, the electronic structures of M₂(O₂CCF₃)₄ (M = Mo, Rh) are studied. Variable energy photon experiments reveal a predominance of ligand character in the M-M σ and π orbitals, despite the relatively poor overall electron donor ability of the ligand. The means by which such a ligand can interact by symmetry with these metal orbitals are studied by computational methods. Finally, the bonding in M₂(mhp)₄ (M = Cr, Mo, W, Ru, Rh) systems is probed. The lower symmetry of these molecules and the intermediate donor properties of this ligand set allow for correlation with the electronic structures of M₂(form)₄ and M₂(O₂CCF₃)₄. Unlike for the higher symmetry systems, ligand involvement in the M-M δ bond is observed and can be understood in terms of molecular symmetry arguments.
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Razgoniaev, Anton. "Design, synthesis, and characterization of photoresponsive materials usingcoordination bonds and other supramolecular interactions." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510918007338796.
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McIntosh, Alan Paton. "Reaction of phosphorus containing compounds with transition metal multiple bonds." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/30483.
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Smith, Jennifer. "Novel iridicycles for the asymmetric reduction of C=N bonds." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2049619/.
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The asymmetric reduction of imino bonds is a well known and utilised method of chiral amine synthesis. Chapter 1 gives an insight into the published methods for a range of substrates via hydrogenation and transfer hydrogention systems. This thesis presents a range of novel iridicycles, all of which contain chiral oxazoline and imidazoline ligands. The synthesised complexes demonstrate a variety of electronic and steric properties. Their activities are presented in the latter chapters for the asymmetric reduction of C=N bonds. Chapter 3 demonstrates the activity of the 4,5,6-trimethoxyimidazoline iridium complex for direct asymmetric reductive amination. High activity, yielding up to quantitative product is reported, under unusually mild conditions, in both aqueous and organic solvent systems. The enantioselectivites achieved were moderate to high for the substrates screened. The use of a bulky 2,4,6-tri-iso-propyloxazoline iridium complex is reported for the asymmetric reduction of quinolines, via transfer hydrogenation conditions. The tetrahydroquinolines were produced in high yields and moderate enantioselectivities. The addition of co-solvents to the aqueous system yielded improved enantioselectivies and conversions. For the reduction of pyridinium salts a bromo-dioxole imidazoline iridium complex presented high activity. This presents unprecedentedly mild conditions via a transfer hydrogenation system, producing high yields of N-benzyl piperidines. The enantioselectivites determined were high, although some could not be measured by the available means. The 2,4,6-tri-iso-propyloxazoline iridium complex further demonstrates high activity and enantioselectivity for the asymmetric hydrogenation of acyclic imines. An NMR and mechanistic study revealed the in-situ formation of a new iridium species present only in TFE.
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Bronk, Brian Scott 1967. "New methods for the formation of carbon-carbon bonds via organometallic compounds." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35441.
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Baxter, Rodney Charles. "The thermodynamics of binary liquid mixtures of compounds containing multiple bonds." Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1016079.
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Excess thermodynamic properties have been determined for several binary liquid mixtures with the aim of testing various thermodynamic theories and postulates. Excess molar enthalpies, HEm, have been determined using an LKB flow microcalorimeter and excess molar volumes, VEm, have been determined using an Anton Paar vibrating tube densitometer. The activity coefficients at infinite dilution ƴ∞₁₃, have been determined using an atmospheric pressure gas-liquid chromatograph. The excess molar enthalpies and the excess molar volumes have been measured at 298.15 K for systems involving the bicyclic compounds decahydronaphthalene (decalin), 1,2,3,4-tetrahydronaphthalene (tetralin), bicyclohexyl, or cyclohexylbenzene mixed with 1- hexene, 1-hexyne, 1-heptene, 1-heptyne, cyclohexene, 1,3-cyclohexadiene, 1,4- cyclohexadiene, or benzene. These excess properties have also been measured for systems where the bicyclic compound has been replaced with benzene, cyclohexane or n-hexane. The results show defmite trends related to the size, shape, and the degree of unsaturation of the component molecules. The Flory theory has been used to predict excess molar enthalpies and excess molar volumes for {(a bicyclic compound or benzene or cyclohexane or n-hexane) +(an n-alkane or a 1-alkene or a 1-alkyne or a cycloalkane or cyclohexene or a cycloalkadiene or benzene)}. The one parameter equations offer reasonably good correlations between the predicted and the experimental results. More insight into the origins of the contnbutions to the excess thermodynamic properties for these systems has been gained by considering the approximate equations of Patterson and co-workers, which separate the interactional and the free volume contributions to the excess molar enthalpy and the excess molar volume. The one parameter equations have adequately rationalized a good deal of the observed behaviour for HEm and VEm. The theory of Liebermann and co-workers, which does not employ any adjustable parameters, has not been as successful at predicting the excess thermodynamic properties for the above systems. The activity coefficients at infinite dilution have been measured at 278.15 K, 288.15 K and 298.15 K for n-bexane, 1-bexene, 1-hexyne, n-heptane, 1-heptene, 1-heptyne, cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, and benzene, in decalin, tetralin, bicyclohexyl, and cyclohexylbenzene. Solvent losses from the column have been accounted for by an extrapolation procedure. The activity coefficient results together with the HEm and VEm values have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution. The partial molar excess properties at infinite dilution for decalin mixtures are similar to those for bicyclohexyl mixtures. There is also a similarity between the properties of the tetralin mixtures and the cyclohexylbenzene mixtures. The cycloalkadienes, benzene and the 1-alkynes exhibit a strong dissociation effect on being mixed with the saturated solvents, decalin and bicyclohexyl, but associate strongly with tetralin and with cyclohexylbenzene. The Flory theory bas been used to predict activity coefficients at infinite dilution from the experimentally determined HEm results for { (n-bexane or 1-hexene or 1-hexyne or naheptane or 1-heptene or 1-beptyne) + (a bicyclic compound)}. The theory is much better at predicting values for mixtures where both components are either saturated molecules or are unsaturated molecules than for {saturated + unsaturated} mixtures.
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King, Evan. "Metal-Ligand Multiple Bonds in High-Spin Complexes." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10356.
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The chemistry of late first row transition metals supported by dipyrromethane and dipyrromethene ligands bearing sterically bulky substituents was explored. Transition metal complexes (Mn, Fe, Co, Ni, Zn) of the dipyrromethane ligand 1,9-dimesityl-5,5-dimethyldipyrromethane (dpma) were prepared. Structural and magnetic characterization (SQUID, EPR) of the bis-pyridine adducts \((dpma)Mn(py)_2\), \((dpma)Fe(py)_2\), and \((dpma)Co(py)_2\) showed each tetrahedral divalent ion to be high-spin, while square planar \((dpma)Ni^{II}(py)_2\) and tetrahedral \((dpma)Zn(py)_2\) were shown to be diamagnetic. Electrochemical experiments revealed oxidative events at common potentials independent of metal identity or spin state, consistent with ligand-based oxidation. Dipyrromethene ligand scaffolds were synthesized bearing large aryl \((Ar = 2,4,6-Ph_{3}C_{6}H_{2}, Mes = 2,4,6-Me_{3}C_{6}H_{2})\) or alkyl \((^{t}Bu = CMe_3, Ad = 1-adamantyl)\) flanking groups to afford three new disubstituted ligands \((^{R}dpme, 1, 9-R_2-5-mesityldipyrromethene, R = Ar, Mes, ^{t}Bu, Ad)\). While high-spin \((S=2)\), four-coordinate iron complexes of the type \((^{R}dpme)FeCl(solv)\) were obtained when R was Mes, tBu, or Ad, use of the sterically encumbered aryl-substituted ligand gave a three-coordinate high-spin \((S=2)\) complex \((^{Ar}dpme)FeCl\). Intramolecular C−H amination was discovered in the reaction of organic azides with \((^{Mes}dpme)FeCl(thf)\), though no intermediate was observed by UV/Vis, IR, or \(^{1}H\) VT-NMR experiments. Reaction of \((^{Ad}dpme)FeCl(OEt_2)\) with alkyl azides resulted in the catalytic amination of C–H bonds or aziridination of olefins at room temperature. Reaction of \(p-^{t}BuC_{6}H_{4}N_{3}\) with \((^{Ar}dpme)FeCl\) permitted isolation of a high-spin \((S=2)\) iron complex \((^{Ar}dpme)FeCl(N(p-^{t}BuC_6H_4))\), featuring a terminal imidyl radical antiferromagnetically coupled to high-spin \(Fe^{III}\), as determined by \(^{1}H\) NMR, X-ray crystallography, and \(^{57}Fe\) Mössbauer. A three-coordinate CoI complex \((^{Ar}dpme)Co(py)\) was synthesized and characterized by \(^{1}H\) NMR, SQUID magnetometry, and X-ray crystallography. Reaction of \((^{Ar}dpme)Co(py)\) with \(^{t}BuN_3\) afforded an isolable three-coordinate Co imide complex \((^{Ar}dpme)Co(N^{t}Bu)\) that exhibits spin crossover from a singlet to a quintet. Reaction of \((^{Ar}dpme)Co(py)\) with mesityl azide produces a spectroscopically observed intermediate, consistent with an \(S=1\) terminal imide complex, that converted via benzylic C–H activation into the metallacycloindoline \((^{Ar}dome)Co(\kappa^{2}-NHC_{6}H_{2}-2,4-Me_{2}-6-CH_2)\).Chemistry and Chemical Biology
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Fincham, Christopher I. "Replacement of peptidic amide bonds in drug design." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239080.
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Acho, Jacqueline A. "Reductive coupling, and, transition metal calixarene complexes : metal-metal quadruple bonds and pockets." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32149.
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Jack, J. James. "Properties of CH bonds in cobalt, tin and zinc alkyl compounds." Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287607.
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This thesis describes the results of a detailed vibrational study on a series of mainly methyl, but also certain ethyl containing organometallic compounds. The primary objective of the work is to show that 'isolated CD' frequencies, vis CD measured from a CH2D group, can be used to provide predictions of CH bond parameters (CH bond length (roCH), HCH bond angle (αHCH) etc.) equally as well as 'isolated CH' frequencies, visCH measured from a CHD2 group. From a review of spectroscopic data in the literature it is apparent that visCD, can be linearly related to visCH. The 98% correlation coefficient for the visCD versus visCH plot illustrates the existence of a workable linear relationship. Clearly the existence of such a relationship seems to suggest that the isotopic substitution CH2D removes Fermi and other resonance effects almost as well as the CHD2 isotopic substitution. Moreover, correcting the visCD frequency for the effects of anharmonicity using a variable R correction factor with a maximum variation 0.5% from 1.011 gives a much improved fit. Making use of existing linear correlations between visCH and fundamental CH bond parameters (roCH and αHCH), it has been shown that the determination of the visCD frequency can be used to provide useful predictions of roCH and αHCH. All this can be achieved without the need for deuteration of ligand CH sites, even in complex systems, previously necessary in the determination of visCH frequencies. The CH/CD stretching regions for a series of eight methylpyridinatocobaloxime isotopomers have been studied, frequencies assigned and the geometry of the methyl group determined.
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Hatherley, Jessica. "On the synthesis of N-O bonds in novel heterocyclic systems." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/42965/.
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The origins of these investigations are in the pursuit of heterocycles containing an N-O bond. This project as a whole focusses on developing earlier chance observations made by previous members of the Knight Research Group. Chapter 2 focusses on the synthesis of isoxazoles: 5-membered aromatic rings containing a nitrogen to oxygen bond. The origin of this project was the unexpected observation of a small percentage of isoxazole products in the Group’s earlier synthesis of isoxazolines, which were thought to be the oxidation products arising from using silver nitrate as a catalyst for those cyclisations. It has now been found that by using an excess of silver nitrate, isoxazoles can be selectively formed from the same hydroxylamine precursors. Chapter 3 centres on the viability of obtaining unusual 6-endo-trig products from the iodocyclisation of unsaturated tert-butyl carbonates. This Chapter is connected to the theme of N-O chemistry, as the tert-butyl carbonate starting materials were the unexpected products of a synthesis that had been designed to form hydroxylamines. The initial discovery of these unexpected 6-endo products on iodocyclisation was expanded upon to produce a series of cyclic carbonates with a procedure optimised to maximise the yield of this desired structural isomer. Chapter 4 concentrates on building saturated N-O rings onto existing cyclic systems, including transannular cyclisations - investigating previous reports of rearrangement of N and O during cyclisation and working towards a synthesis of the core-structure of the natural product Histrionicotoxin. These schemes prove the utility of this acid-catalysed hydroamination methodology in building heterocycles and the chiral products that can be gleaned from them. For the most part, this project has been concerned with methodology - solving problems and optimising key-step procedures - which can be applied to complex target molecules.
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Hao, Shoukang. "The paradoxical weakness of very short and supershort M-M multiple bonds." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9625.
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This thesis deals with the syntheses and characterization of a novel series of Cr(II), as well as V(II) complexes. The strength of Cr-Cr quadruple bonds has been investigated experimentally. The Cr-Cr multiple bond of the dimeric (TAACr) $\sb2$ (TAA = tetramethyldibenzotetraaza (14) annulene) (2.1) is reversibly cleaved by pyridine to form monomeric paramagnetic octahedral (TAACrpy$\sb2\rbrack$.py (2.2). The synthesis, characterization and stability properties of a novel series of Cr(II) alkylchromates together with their transformation into unprecedented alkylidene (Schrock-type) Cr(III) species, and Cr(II) and Cr(III) metallacycles is described in chapter 4. The ability of three center chelating ligands to form dichromium units and to enforce short and very short Cr-Cr contacts is examined in a consistent series of cyclohexyl amidinate chromium complexes, with the aim of understanding the factors intrinsic in the nature of the bridging ligands which are able to promote or disfavor dinuclear aggregation and to determine the extent of intermetallic separation. The synthesis and characterization of a new series of mono-, di- and trinuclear Cr(II) borohydride compounds is described in chapter 7. The reaction of CrCl$\sb2$(TMEDA) with two equivalents of NaBH$\sb4$ afforded the thermally unstable (TMEDA)Cr(BH$\sb4)\sb2$ (7.1) which was converted by treatment with pyridine into the octahedral monomeric (Py)$\sb4$Cr(BH$\sb4)\sb2$ (7.2). Reaction of V(II) and V(III) salts with lithium amidinates formed a series of compounds where both the nuclearity and the oxidation state of the final complex were determined by the steric bulk of the substituents of the amidinate ligand. While dinuclear compounds with and without short V-V contacts have been obtained in the case of formamidinate anions, monomeric complexes and a dinuclear end-on dinitrogen complex were formed with the more bulky acetamidinate and trimethylsilyl benzamidinate. The reaction of VCl$\sb2$(TMEDA)$\sb2$ and of VCl$\sb3$(THF)$\sb3$ with two equivalents of formamidinate lithium salts respectively yielded dimeric $\rm \{\lbrack CyNC(H)NCy\rbrack\sb2V\}\sb2$ (8.2), with a very short V-V multiple bond, and $\rm \{\lbrack CyNC(H)NCy\rbrack\sb2VCl\}\sb2$ (8.4) which is also dimeric. The dinuclear structure was reversibly cleaved by treatment with pyridine forming the monomeric (CyNC(H)NCy) $\sb2$V(Py)$\sb2$ (8.3). Conversely, similar reactions with acetamidinate anion gave only the monomeric (CyNC(Mc)NCy) $\sb2$V- (THF)$\sb2$ (8.5a) and (CyNC(Me)NCy) $\sb2$VCl (8.7) respectively. Attempts to form a dinuclear structure by either removal of THF from 8.5a or reduction of 8.7 gave only the V(III) compound (CyNC(Me)NCy) $\sb3$V (8.6). Finally, reaction of VCl$\sb2$(TMEDA)$\sb2$ with two equivalents of carboxylic acid in THF in the presence of a slight excess of TMEDA at room temperature, afforded the large scale preparation of the linear V(II) trimer V$\sb3$(R$\sb2$CHCOO)$\sb6$(TMEDA)$\sb2$ (R = Ph$\sb2$CH (9.1), PhCH$\sb2$ (9.2)). Cleavage of the trimeric unit and formation of a high-spin monomeric species ((R$\sb2$CHCOO)$\sb2$V(pyridine)$\sb4\rbrack$ (9.3) was achieved upon simple treatment of 9.1 with pyridine at room temperature. The structures of 9.1 and 9.2 are demonstrated by X-ray analysis. (Abstract shortened by UMI.)
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Dressel, Jürgen. "Through-bond interaction of two mutually perpendicular [pi]-ribbons through a cyclobutane relay /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487324944214397.
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Dunham, Veronica Vin-yi. "Metal-Free Approaches to Sterically-Hindered Bonds." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1467360601.
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McGrellis, Siobhan Ann. "Structure and chemistry of some low valent transition metal oxides containing metal-metal bonds." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384902.
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Flint, Bruce W. "Exploring the bonding and reaction chemistry of gold and platinum complexes /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3036824.
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Chakraborty, Arundhoti. "Development of Copper Catalysts for the Reduction of Polar Bonds." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479814963555246.
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Hutchinson, Louise. "The use of arrays of oriented hydrogen bonds to form supramolecular devices." Thesis, Northumbria University, 2007. http://nrl.northumbria.ac.uk/3606/.
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A group of simple amide receptors were synthesised to investigate the effect varying the number/type of hydrogen bond donors or in preorganisation has on host/guest binding abilities. Proton NMR titrations revealed preorganised nitrogen atoms could reduce the size of the binding cleft increasing the selectivity for the smaller anions and binding affinities were increased by the addition of additional hydrogen bond donors, increasing the size of the binding cleft and the presence of sulphonamide groups. A number of receptors were also investigated as colorimetric sensors and visual colour changes were observed with the addition of guest, however further investigations revealed these could be due to deprotonation of the receptor. A fluorescent cation was also synthesised which proton NMR titrations proved had increasing binding affinities. Fluorescence titrations showed the addition of guest increased the fluorescence intensity suggesting it could possibility be used for calculating the concentration of chloride in serum samples. Cyclotrimeric receptors containing three urea/thiourea moieties were successfully synthesised by a one-pot cyclotrimerisation. However they proved to be very insoluble preventing purification and investigations of their binding ability. The presence of TBA nitrate proved to have a templating effect in the synthesis of the thiourea cyclotrimer but not the urea cyclotrimer. A step-wise cyclotrimerisation was not possible due to the lack of solubility of the products from step-one for the urea receptor and step-two for the thiourea. However Proton NMR titrations of these receptors revealed the urea/thiourea hydrogen bond donors formed stronger interactions with anionic guests than the previous amide receptors. Finally a number of substrates containing alkene moieties and bis-urea/thiourea receptors were synthesised in the hope of templating cycloaddition photochemical reactions forcing the formation of head-to-head photodimers. Unfortunately cycloaddition photochemical reactions were unsuccessful due to the lack of solubility of both the receptors and substrates preventing any investigations being carried out.
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Hassan, Mohammad Khadiga Abdul Rahman. "Synthesis and characterization of species containing W-S or W-Se bonds." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292727.
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Chakma, Progyateg. "Introducing Adaptability in Polymer Networks Through Dynamic Thiol-Michael Chemistry and Nucleophilic Substitution." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1593636035333397.
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Gooseman, Natalie. "The influence of the C-N⁺------F-C charge dipole interaction in fluoro organic chemistry /." St Andrews, 2008. http://hdl.handle.net/10023/695.
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Jeenjitkaew, Choothum. "Kissing bonds in adhesive joints : a holistic approach for surface chemistry and joint mechanics." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1269.
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Kissing bonds (KBs) refer to the situation where two surfaces are only partially bonded or are debonded but touching or in very close proximity. This may be the consequence of poor adhesion, environmental degradation or impact damage. This defect is not visible macroscopically and because of their intimate contact which makes it more difficult to detect using a non destructive technique (NDT) than conventional defects such as voids or cracks etc. The success of NDT evaluation and widespread use of adhesive bonding rely greatly upon comprehensive knowledge of morphology, surface chemistry and mechanics associated with KBs. Two approaches were successfully taken to produce reliable and repeatable KBs: by surface contamination using a mould release agent (Frekote®700-NC); and by weakening the electrically-debonding adhesive, ElectRelease™, with a low voltage. Significant changes in morphology and elemental distribution of the contaminant at/near the Frekote contaminated interfaces were found. Some morphological and chemical changes at/near the anodic metal/ElectRelease™ interface were also evident. Additional information about chemical interactions at/or near the contaminated interface due to the presence of Frekote and the application of the electric field confirmed the changes in morphology and elemental distribution. Double-lap joints with KBs were tested in tension with local strains captured by strain gauges and extensometer. Significant reduction in failure strength was apparent when using Frekote and ElectRelease™ subjected to the electric field. The tests were simulated using finite element analysis. Cohesive elements were introduced along the predicted failure interfaces taking into account the adhesion loss associated with KBs. The experimental failure load and local strain results were in good agreement with the finite element predictions. The ways that KBs were produced and the understandings in morphology, surface chemistry and their failure mechanisms contributed to the modified criteria of KBs and the development of the non-linear ultrasonic technique investigated by the NDT group at the University of Bristol. The morphology, surface chemistry and failure mechanisms of KBs in adhesive joint are now better understood.
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Oswald, Sönke. "Weak Hydrogen Bonds to Molecular Nitrogen and Oxygen as Experimental Benchmarks for Quantum Chemistry." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/11858/00-1735-0000-002E-E5E0-3.
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Kilgore, Uriah J. "Synthesis, characterization, and reactivity of early transition metal complexes bearing metal-ligand multiple bonds." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3354902.
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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2009.Title from PDF t.p. (viewed Feb. 4, 2010). Source: Dissertation Abstracts International, Volume: 70-04, Section: B, page: 2297. Adviser: Daniel J. Mindiola.
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Jenkins, Timothy Andrew. "Short strong hydrogen bonds studied by inelastic neutron scattering and computational methods." Related Electronic Resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2003. http://wwwlib.umi.com/cr/syr/main.
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