Dissertations / Theses on the topic 'N-Heterocyclic carbenes complexes'
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Lerma, Israel Consea. "Transformations Mediated by Palladium-(N-Heterocyclic)Carbenes Complexes." Thesis, University College London (University of London), 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498701.
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Mungur, Shaheed Ali. "Electropositive metal complexes of amino N-heterocyclic carbenes." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415893.
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McNally, C. T. "Transition metal complexes of pyridyl functionalized n-heterocyclic carbenes." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546329.
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Silcock, Peter J. "Nickel and palladium complexes of di-N-heterocyclic carbenes." Thesis, University of Oxford, 1999. https://ora.ox.ac.uk/objects/uuid:679dade4-1d16-4918-b155-996250516783.
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This thesis is concerned with the synthesis of two di-N-heterocyclic carbene ligands, and their reactivity towards nickel and palladium precursors in order to synthesise new organometallic pre-catalysts for a number of important reactions. The catalytic properties of a new rhodium C60 compound are also investigated, with relevance to the evaluation of C60 as a hydrogen storage medium. Chapter 1 reviews the preparation and chemistry of N-heterocyclic carbenes, emphasising their organometallic reactivity and role as ancillary ligands in homogeneous transition metal catalysis. An overview of relevant nickel and palladium catalysis is also presented, including olefin polymerisation, olefm / CO copolymerisation and Heck coupling reactions. Chapter 2 describes the synthesis and characterisation of the dicarbene ligands tBuCCmeth and tBuCCeth and their reactions with various nickel precursors in attempts to prepare chelating dicarbene nickel cis-dihalide complexes. The synthesis, characterisation and chemical reactivity of the cations [Ni(tBuCCmeth)2]2+, [(tBuCCmeth)NiCl(PMe3)] + and [(tBuCCeth)NiCl(PMe3)]+ is detailed, and their X-ray structures are compared. The unsuccessful preparation of [Ni(tBuCCeth)2] 2+ and the relative stability of the monocations with respect to dicarbene substitution is discussed and attributed to steric factors. Chapter 3 describes the synthesis, characterisation, reactivity and catalytic studies of simple nickel and palladium cis-dimethyl complexes of the chelating dicarbene ligands. Variable temperature 1H NMR spectroscopy showed contrasting rates of thermal hydrocarbon elimination from Ni(tBuCCmeth)Me2 and Ni(tBuCCeth)Me2, which has previously been observed for chelating bis-phosphine analogues with various P,P' linkages (CH2)n . These observations further corroborate the analogy between dicarbene and 6/s-phosphine ligands. It was demonstrated that the compounds Pd(tBuCCmeth)Me2and Pd(tBuCCeth)Me2 are effective pre-catalysts for the Heck coupling of 4-bromoanisole and n-butyl acrylate. In addition cations of the type [(tBuCCmeth/eth)PdMe(L)]+ (L = pyridine, THF) which are relevant to olefin / CO copolymerisation were prepared. The X-ray structures of M(tBuCCeth)Me2 (M = Ni, Pd) are discussed as well as the synthesis and structural characterisation of [(|Li-tBu CC meth){Ni(PMe3)Me2}2]. Chapter 4 presents a brief introduction to some relevant C60 chemistry and to the concept of hydrogen storage. The synthesis and characterisation of a new rhodium Ceo compound is described. The compound catalysed the hydrogenation and hydroformylation of simple alkenes as well as the hydrogenation of C60 to C60H36 . The recovery of hydrogen gas from C60H36 was investigated in order to evaluate C60 as a hydrogen storage medium. Chapter 5 outlines the experimental details for the synthesis, characterisation, reactions and catalytic studies of the new compounds described in the preceding three chapters. Chapter 6 presents the characterising data for the new compounds described in chapters 2 and 3. Appendices contain details of the crystallographic data for the eight structurally characterised compounds described in chapters 2 and 3.
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Brayshaw, Simon Keith. "Metal complexes bearing pendant alkynes and metal complexes of N-heterocyclic carbenes." University of Western Australia. School of Biomedical and Chemical Sciences, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0017.
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This thesis is comprised of two parts. The first part describes the synthesis of cyclopentadienyltungsten complexes containing a pendant alkyne group (I), and the subsequent photo-induced intramolecular coordination of the alkyne, forming complexes such as II. Compounds containing intramolecularly coordinated alkynes are rare, and this is the first example using cyclopentadiene as the core ligand. The second part describes the synthesis and structural characterisation of a number of novel metal complexes containing N-heterocyclic carbene ligands, some containing particular functionality for taylored applications. New methods were used to form complexes of rhodium, iridium, silver and gold (eg. III, IV). Structural and spectroscopic properties of the complexes were correlated with electronic characteristics of the ancillary ligands. A number of rhodium and iridium complexes (eg. IV) derived from imidazolium-linked cyclophanes were synthesised and structurally characterised. Complexes of N-heterocyclic carbenes with pendant ionic groups were synthesised, and a preliminary examination of their catalytic activity in water was performed. N-Heterocyclic carbenes complexes containing an electron withdrawing nitro group were synthesised and the effect of the nitro group on metal-ligand bonding was examined.
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Martin, Thomas Antony. "Unravelling the photochemistry of organometallic N-heterocyclic carbene complexes." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547630.
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This thesis describes the synthesis, characterisation and reactivity of new manganese and rhenium(I) NHC complexes, which have been investigated both thermally and photochemically and the results contrasted with existing phosphine analogues in the literature. Cp’Mn(CO)2(NHC) (NHC = IEt2Me2 1, IMes 2, IiPr2Me2 3 and IPr 4) were synthesised and investigated by TRIR spectroscopy. Loss of CO was observed after 355 nm irradiation to form agostically stabilised intermediates, which reformed the parent species by recombination with CO on the nanosecond timescale. Loss of NHC was not observed, in contrast to Cp’Mn(CO)2(PPh3) which lost both CO and PPh3 upon photolysis. [Re(NHC)(Bpy)(CO)3]BAr4F (NHC = IEt2Me2 5, IMes 6) were synthesised and investigated by TRIR spectroscopy and UV/Vis absorption and emission spectrometry. Inclusion of an NHC altered the excited state manifold of the complexes, favouring population of the 3MLCT over the 3IL excited state. The lowest energy excited state for both 5 and 6 proved to be a 3MLCT excited state at 298 and 77 K. In contrast, [Re(PPh3)(Bpy)(CO)3]BAr4F exhibited 3MLCT at 298 K, but 3IL at 77 K. A series of complexes, M(NHC)(CO)4X and M(NHC)2(CO)3X (M = Re, X = Cl; M = Mn, X = Br) formed upon reaction of the corresponding M(CO)5X species and free NHC. The substitution pattern was dictated by the steric bulk of the NHC. Generation of the corresponding cations by halide abstraction was investigated. M(NHC)2(CO)3X was found to form agostic stabilised species upon halide abstraction by NaBAr4F in CH2Cl2. Under the same conditions, Re(IPr)(CO)4Cl was found to form the dichloromethane complex, [Re(IPr)(CO)4(η1-CH2Cl2)]BAr4F. In C6H5F solution under an atmosphere of dihydrogen, the CH2Cl2 ligand could be displaced by H2 to form the dihydrogen species, [Re(IPr)(CO)4(H2)]BAr4F.
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Conti, Riccardo. "Synthesis of novel N-Heterocyclic Carbenes for chiral complexes and catalysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13374/.
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The aim of my training period has been the synthesis of new chiral N-heterocyclic carbene precursors starting from camphoric diacid and the employment of imidazolium salts derived NHC as linker to dendrimers supports for organometallic catalysis. New chiral ligands are needed to develop new catalytic systems for enantioselective transformations. The new type of ligand described was developed starting from camphoric diacid, a cheap chiral molecule, following different synthetic strategies. Asymmetric functionalized chiral NHCs are readily available by methods developed and two of the precursors obtained were employed in preliminary tests with Aluminium and Palladium.
An NHC derived from imidazolium salt has been investigated as linker to dendrimeric supports for tetraarylciclopentadienone-Ruthenium complexes with the aim to combine advantages of homogeneous catalysis to advantages of heterogeneous one, in particular easy recover of catalyst. The functionalized dendrimers obtained have been used in transfer hydrogenation and dehydrogenation reactions. Moreover a new class of functionalized dendrimer was obtained employing a new tetraarylciclopentadienone-Ruthenium complex with trimethyl silyl groups on cyclopentadienone ligand with the aim to change solubility of the system.
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Mokfi, Moloud [Verfasser]. "Xanthine-derived N-heterocyclic carbenes and their metal complexes / Moloud Mokfi." Wuppertal : Universitätsbibliothek Wuppertal, 2021. http://d-nb.info/1240266960/34.
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Turner, Zoe Rose. "Small molecule activation using electropositive metal N-heterocyclic carbene complexes." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/8210.
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The versatility of N-heterocyclic carbenes (NHCs) is demonstrated by numerous practical applications in homogeneous transition metal catalysis, organocatalysis and materials science. There remains a paucity of electropositive metal NHC complexes and so this chemistry is poorly developed with respect to that of the late transition metal and main group elements. This thesis describes the synthesis of new alkoxy-tethered NHC proligands, their use in the synthesis of reactive metal amide and metal alkyl complexes, and finally small molecule activation using these complexes. Chapter One introduces NHCs and discusses their use as supporting ligands for early transition metal and f-block complexes. Small molecule activation using organometallic complexes is examined alongside the use of electropositive metal NHC complexes in catalysis. Chapter Two contains the synthesis and characterisation of new alkoxy-tethered NHC proligands and a variety of electropositive MII (M = Mg and Zn), MIII (M = Y, Sc, Ce and U) and MIV (M = Ce and U) amide complexes. X-ray diffraction studies and a DFT study are used to probe the extent of covalency in the bonding of the MIV complexes. Chapter Three investigates the reactivity of the amide complexes prepared in Chapter Two. The MII complexes are shown to be initiators for the polymerisation of raclactide into biodegradable polymers. The MIII complexes are used to demonstrate additionelimination reactivity of polar substrates across the M-Ccarbene bond which allows the formation of new N-E (E = Si, Sn, P or B) bonds. Treatment of the UIII silylamide complex U(N{SiMe3}2)3 with CO results in the reductive coupling and homologation of CO to form an ynediolate core -OC≡CO- and the first example of subsequent reactivity of the ynediolate group. The MIV complexes are used to examine the potential for forming MIV cationic species and alkyl complexes. Chapter Four examines the synthesis of MIII (M = Ce and Sc) aminobenzyl complexes and MIII (M = Y, Sc and U) neosilyl and neopentyl alkyl complexes. The addition-elimination reactivity discussed in Chapter Three is extended to include C-E bond formation (E = Si, Sn, P, B, I or C). Chapter Five provides overall conclusions to the work presented within this thesis. Chapter Six gives experimental and characterising data for all complexes and reactions in this work.
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Hesler, Valerie Jane. "N-Heterocyclic carbene-metal complexes derived from imidazolium-linked cyclophane and biimidazolium salts." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0088.
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This thesis presents an investigation into the synthesis of metal complexes of (Nheterocyclic carbene)-based cyclophanes. There were three main areas of focus: synthesis and complexation of bis(4,5-dihydroimidazolium) salts; the synthesis and complexation of phenol-functionalised imidazolium cyclophanes; and the synthesis and complexation of (N-heterocyclic carbene)-based cyclophanes by C-C bond activation of biimidazolium salts with electron-rich metals. The synthesis of xylyl-linked bis(4,5-dihydroimidazolium) salts was investigated. Attempts to prepare these compounds by the cyclisation of a tetraamine (linear or macrocyclic) were unsuccessful due difficulties in preparing the tetraamines. The target compounds could be prepared by adapting the methods developed for the synthesis of bis(imidazolium) salts however problems associated with purification and stability of the products prevented complexation studies. A series of phenol-, phenoxide- and anisole-functionalised imidazolium cyclophanes were prepared. Their structural properties were investigated using dynamic nmr studies and X-ray crystallography. Complexation of the functionalised cyclophanes was investigated. The phenol cyclophane I formed a dinuclear complex with mercury(II). This complex is the first example of a complex derived from a phenol-functionalised imidazolium cyclophane. However the anisole cyclophane II and the unsymmetrical phenol/ortho cyclophane III were unable to form complexes possibly due to steric hindrance and instability of the cyclophane respectively. Preliminary complexation studies of the bis(imidazolium)phenol V suggested that complexation with palladium(II) and mercury(II) were possible but more work is required to determine the optimum reaction conditions. A series of biimidazolium salts VI (both new and known) were prepared. Previously reported biimidazolium salts have very low solubility in common solvents therefore the incorporation of long alkyl chains to the bridging group was investigated as a means to improve the solubility. The structure of the salts was explored using a range of techniques including dynamic nmr spectroscopy, cyclic voltammetry, UV/Visible spectroscopy, X-ray crystallography and mass spectrometry. Some of the biimidazolium salts were able to rotate about the C2-C2' bond and the free energy of activation for this process was estimated using dynamic nmr studies. C-C bond activation of the biimidazolium salts with palladium(0) was used to form a series of palladium(II) complexes (VII) of (NHC)-based cyclophanes. These reactions are the first examples of the synthesis of bis(NHC) complexes by C-C bond activation. The reactivity of the biimidazolium salts with palladium(0) was compared to their solution structure and it was found that only the biimidazolium that were able to rotate about the C2-C2' bond could react with palladium(0).
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Poulten, Rebecca. "Synthesis and reactivity of low coordinate nickel(I) complexes bearing ring expanded N-heterocyclic carbene ligands." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669038.
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This thesis describes the development of nickel(I) complexes incorporating ring expanded N-heterocyclic carbene (RE NHC) ligands and examines their electronic characterisation, activation of O2, reactivity and catalytic applications. A series of three coordinate, paramagnetic Ni(I) complexes of the form Ni(RE NHC)(PPh3)Br (1 – 10) were prepared by comproportionation of Ni(COD)2 and Ni(PPh3)2Br2 in the presence of RE NHCs. The RE NHCs employed varied in the degree of ring expansion (6-, 7- and 8-membered), extent of N-substituent steric bulk (Mes, oTol, oAnis) and the donor/acceptor properties of the carbene (diamino vs. diamido). EPR and DFT electronic characterisation of 1 – 10 confirmed that the unpaired electron was located on the nickel ion in a mixed orbital of predominantly 3dz2 character. Yellow solutions of 1 or 6 (RE NHC = 6Mes and 7Mes respectively) immediately became purple in the presence of O2 due to O2 activation and incorporation of the oxygen atoms as bridging ligands resulting from C-H activation/oxygenation of an RE NHC N-substituent. This generated the dimeric Ni(II) complexes Ni(6/7Mes)Br(µ-OH)(µ-O-6/7Mes)’NiBr (6Mes = 13; 7Mes = 14). Mass spectrometry demonstrated that the doubly activated complexes [NiBr(µ-O-6/7Mes)’]2 (15 and 16 respectively) were also formed in the reactions. UV-vis spectroscopy revealed the reactions took place rapidly, even at 190 K. Contrasting reactivity was observed when 2 or 7, bearing the less sterically encumbered N-oTol substituents 6oTol and 7oTol respectively, were exposed to O2, which led to the ligand redistribution products NiII(6/7oTol)(PPh3)Br2 (17 and 18 respectively). The less electron rich diamido analogue containing 6MesDAC (5), underwent dissociation and oxidation of the RE NHC and PPh3 ligands. Attempts to abstract the bromide from 1 generated novel two and three coordinate Ni(I) products. Reaction with additional 6Mes produced the two coordinate cation [Ni(6Mes)2]+ (19), which could be reduced with KC8 to Ni(6Mes)2 (20). SQUID analysis of 19 revealed it to be the first example of a nickel containing mononuclear single molecular magnet (SMM). Addition of [Et3Si]+ to 1 followed by work up in toluene led to the isolation of the Ni(I)-(η2-toluene) complex [Ni(6Mes)(η2-C6H5CH3)]+ (21). Mesitylene generated the analogous [Ni(6Mes)(η2-C6H3(CH3)3)]+ (23), but neither 1,4-xylene nor naphthalene gave isolable products. In all cases, cocrystallisation of [6MesH]+…arene was observed in variable amounts, which compromised reaction studies of the Ni-arene complexes. Removal of bromide from 1 with TlPF6 in THF generated the solvent coordinated cationic species [Ni(6Mes)(PPh3)(THF)]+ (24). Attempts to remove the ligated THF molecule were unsuccessful, however, it could be directly substituted by CO to form [Ni(6Mes)(PPh3)(CO)]+ (26). Similarly to 1, complex 24 activated O2, generating a dimer analogous to the singly activated complex 13 (Ni(6Mes)(PPh3)(µ-OH)(µ-O-6Mes)’NiBr (25)). Reactivity of 1 with NaBH4 produced [Ni(6Mes)(κ2-BH4)]2 (28), a Ni(I) dimer bridged by two BH4 ligands. The catalytic efficiency of neutral 1 in Kumada cross-coupling of aryl halides and PhMgCl or MesMgBr was probed. Of note was the high activity towards both aryl chlorides and aryl fluorides. Comparisons with cationic 24, larger 7- (7) and 8-membered ring (8 and 9) variants and the Ni(II) complexes Ni(6Mes/6oTol/7oTol)(PPh3)Br2 (29, 17 and 18 respectively) revealed that 1 exhibited the highest reactivity of all the precursors.
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Durmus, Semih. "Silver(I) and Gold(I) N-Heterocyclic Carbene Complexes." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1165247084.
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Haque, Rosenani S. M. Anwarul. "Silver, mercury and ruthenium complexes of N-heterocyclic carbene linked cyclophanes." University of Western Australia. Chemistry Discipline Group, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0236.
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This thesis describes the synthesis and isolation of silver, mercury, ruthenium and palladium complexes of bidentate N-heterocyclic carbenes (NHCs), derived from imidazolium-linked cyclophanes and related bis-imidazolium salts. The cyclophane structures contain two imidazolyl links between ortho- and meta- substituted aromatic rings and the related structures are ortho-, meta- and para-xylyl linked bis-imidazolium salts. The complexes have been characterised by NMR spectroscopy and X-ray crystallography. The synthesis of five new silver complexes has been achieved via a simple complexation reaction of the cyclophane and bis-imidazolium salts with the basic metal source Ag2O. The new silver carbene systems are thermally stable. Three of the complexes are dinuclear, cationic complexes, while two are mononuclear complexes, one cationic and one neutral. A number of mono- and di-nuclear mercury(II)-NHC complexes have been synthesised from the ortho- and meta-linked cyclophanes and the related meta-linked bis-imidazolium salts. The mercury complexes were prepared by direct mercuration method using mercury(II) acetate. The syntheses were perfomed in air and the complexes are stable to air and moisture. Mercury complexes I and II represent the first example of mononuclear metal complexes derived from meta-substituted imidazolium-linked cyclophanes. NHC-ligand transfer reactions from NHC-silver complexes and NHC-mercury complexes are described. An ortho-cyclophane ligand was successfully transfered from a silver complex to its palladium counterpart. Furthermore, palladium complex III, bearing a para-xylyl linked bis-NHC ligand, was made by transmetallation from both a silver and mercury complex. This is the first reported NHC-palladium complex of a para-xylyl linked bis-NHC ligand. A new redox transmetallation method for NHC ligand transfer, using a mercury complex, is presented. A palladium complex was made via redox transmetallation using a mercury complex of an ortho-NHC-cyclophane. A ruthenium(II)-NHC complex, IV containing an ortho-cyclophane ligand has been prepared via silver transmetallation and in situ complexation methods. In the transmetallation route, a silver complex of an ortho-cyclophane was treated with RuCl2(PPh3)3 to form IV. This complex represents the first example of a ruthenium complex bearing an NHC-cyclophane ligand, v and is also the first example of a metal complex derived from an imidazolium-linked cyclophane where the arene unit of the cyclophane is also involved in bonding to the metal centre.
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Dupuy, Stéphanie. "N-heterocyclic carbene gold hydroxide complexes as bond activation reagents." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6613.
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Although known since the 1930s, organogold chemistry has been dormant until recently, primarily due to preconceptions about the inertness of gold in transformations. However, this last decade has witnessed the emergence of a Golden Age with the development of a wealth of reports on gold in a plethora of reactions. In recent years, the drive for more atom- and step-economical and environmentally friendly reactions has become a field of intense research. In our on-going research on well-defined transition metal complexes bearing NHC ligands, our group recently discovered a new gold(I) hydroxide complex [Au(OH)(IPr)] (1a) that can be easily synthesised from the chloride precursor [AuCl(IPr)] (1b). A preliminary survey of the reactivity of this gold synthon has demonstrated interesting reactivity that holds great potential in bond activation reactions and the development of useful synthetic methods. Simplistically, this gold hydroxide complex can be seen as a strong Brønsted base. This thesis is dedicated to an in-depth examination of the reactivity of this complex in base-free bond activation reactions. Two themes predominate in the following chapters: the first part demonstrates the activity of gold(I) hydroxide as a bond activation agent to readily and efficiently access organogold complexes while the second part studies the reactivity of this compound in decarboxylation processes with carboxylic acids. Chapter 2 and 3 were dedicated to the development of new synthetic routes to access organogold complexes via base-free transmetalation reactions with organoborons and silanes using 1a. The combination of experimental and computational studies allowed identification and isolation of key intermediates in these reactions. Chapter 4 can be seen as a transition between the development of novel methodologies to synthesise aryl and heteroarylgold complexes and the first steps of gold hydroxide 1a as mediator in decarboxylation reaction. As a result, a novel mode of reactivity for gold was discovered and the synthetic route developed constitutes one of the greenest procedures to prepare organogold complexes with the generation of water and CO₂ as only side products. Chapter 5 and 6 venture further into the exploration of 1a in decarboxylation reactions and detail the development of a catalytic process for the protodecarboxylation reaction and subsequent mechanistic investigations of this reaction through stoichiometric experiments and kinetic and computational studies.
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Charra, Valentine. "Coordination of multidentate N-heterocyclic carbene ligands to nickel." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF019/document.
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Le sujet de cette thèse porte sur la synthèse de ligands de type bis-NHC (carbène N-Hétérocyclique) et leur réactivité vis-À-Vis des complexes d’argent(I), de cuivre(I) et de nickel(II).Après avoir exploré les différentes méthodologies de synthèse des complexes de nickel(II) bis-NHC, le but était de tester leurs activités en catalyse d’oligomérisation de l’éthylène. Une série de nouveaux complexes d’argent(I) et de cuivre(I) fut synthétisée. Cinq voies furent testées pour la formation de complexes de nickel. Les résultats les plus probants furent obtenus par transmétallation à partir des complexes d’iodure ou de bromure d’argent(I)The purpose of this work was the synthesis of bis-NHC (N-Heterocyclic carbene) ligands, theformation of the corresponding silver(I), copper(I) and nickel(II) complexes and the assessment ofthe catalytic activity of the bis-NHC nickel(II) complexes in ethylene oligomerization. A series of new bis-NHC silver(I) and copper(I) complexes was synthesized. Five different synthetic routes were tested for the formation of nickel(II) bis-NHC complexes. The most significant results were obtained by transmetalation from the silver(I) iodide or bromide complexes
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Dyson, Gavin. "Synthesis of amine functionalised di-N-heterocyclic carbenes and chiral N-heterocyclic carbene-Schiff base transition metal complexes and their application to homogeneous catalysis." Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440968.
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Melaiye, Abdulkareem M. "Synthesis and Antimicrobial Properties of Silver(I) N-Heterocyclic Carbene Complexes." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1124310734.
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Glover, Leighton Paul. "Transition metal complexes of N-heterocyclic carbenes and their application in homogeneous catalysis." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482842.
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McMullon, Max William. "Exploiting anionically-tethered N-heterocyclic carbene complexes for small molecule activation." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31079.
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N-heterocyclic carbenes (NHCs) can be used as ligands for organometallics complexes, which can then facilitate numerous catalytic applications, such as, C-H activation, small molecule activation and numerous materials applications. The use of anionically-tethered NHCs for usage with electropositive metals has been pioneered by the Arnold group within the last decade. This thesis describes the synthesis of both aryloxide- and amide-tethered NHC organometallic complexes of s-, p-, d- and f-block metals to provide a platform for small molecule activation. Once synthesised, the reactivity of some of these complexes were tested by reaction with CO2 with the aim of turning a molecule considered a harmful (environmentally), waste product into value added products, potentially providing an alternative fuel source. Chapter One introduces the use of anionically-tethered NHCs for use in a number of organometallic complexes as well as their current potential as catalysts for a number of important small molecules. This chapter focuses upon the differences between complexes tethered with anionic O, N, P, S elements, f-element NHC complexes and the use of d-block NHC complexes for catalysis. Chapter Two contains the synthesis and characterisation of a number of aryloxy-tethered NHC p-, d- and f-block organometallic complexes using the ligand H2(LArO R)2. The synthesis of SnII complexes including the synthesis of new ‘normal’ ‘abnormal’ complexes given enough steric bulk around the Sn centre due to the lone pair present in Sn complexes, preventing one of the ligands binding through the classical carbene position and therefore binding through the backbone C4 carbon. The synthesis of MII (Zn, Co and Fe) complexes to compare the solid-state structure and binding mode of the carbenes. The synthesis and characterisation of MIII (Ce and Eu) complexes to assess the solid-state structure and binding modes within f-bock complexes. Chapter Three investigates the reactivity of the MII complexes (Sn, Zn, and Fe) with CO2. Successful reactions were characterised using NMR and further treated with alkynes to target catalytic reactions. Chapter Four contains reactions to target a number of amide-tethered bis (NHC) s-, p-, d- and f-block organometallic complexes using the proligand, H4(LN Mes)Cl3. Deprotonation studies undertaken with a number of bases to give the MI (Li and K) salts and MII (Mg) salts and proved to be unsuccessful upon isolation. Reactions to synthesise the p-, d- and f-block complexes were then undertaken using in situ free carbene production as well as the attempted isolation of the free carbene, both of which also proved unsuccessful. Chapter Five provides an overall conclusion to the work presented in Chapters Two, Three and Four within this thesis. Chapter Six gives the experimental and characterising data for the complexes and reactions.
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Zinser, Caroline Magdalene. "Palladium and gold N-heterocyclic carbene complexes : synthesis and catalytic applications." Thesis, University of St Andrews, 2019. http://hdl.handle.net/10023/17066.
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Gauthier, Étienne. "Chiral complexes based on helicenic N-heterocyclic carbenes : synthesis, structure, photophysical and chiroptical properties." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S083.
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Dans le cadre de ma thèse, de nouveaux complexes de métaux de transitions (rhénium, iridium, cuivre, or) chiraux possédant des ligands NHC-hélicéniques ont été synthétisés et les propriétés chiroptiques et photophysiques ont été étudiées. Le premier sujet d’étude s’est focalisé sur l’étude de complexes de rhénium(I) cyclométallés par des ligands hélicéniques-NHC de type (N^C:) émettant de la phosphorescence circulairement polarisée. Une influence du design du ligand, des ligands ancillaires et de la géométrie des complexes sur les propriétés chiroptiques et photophysiques a été observée. Le deuxième projet a été consacré à l’étude de nouveaux complexes chiraux d’iridium cyclométallés possédant un ou plusieurs ligands N-[6]helicenyl-benzimidazolylidène. L’attention s’est ensuite portée sur des complexes possédant des ligands monodentes. Ainsi, dans le cadre d’un troisième projet, un complexe de cuivre portant un ligand NHC-hélicénique démontrant des propriétés de fluorescence circulairement polarisée a pu être obtenu avec succès. Enfin, des complexes chiraux d’or coordinés par des ligands hélicéniques-NHC ont été préparés. Pendant ce projet, les propriétés électroniques (sigma-donatrice et pi-acceptrice) d’un carbène hélicénique ont été quantifiéesMy PhD work was dedicated to the synthesis and the study of novel chiral transition metal complexes (rhenium, iridium, copper, gold) bearing NHC-helicenes ligands and to the study of their chiroptical and photophysical properties. The first subject focused on the preparation and the study of CP-phosphorescent complexes of cyclometalated rhenium(I) complexes bearing NHC-helicenic (N^C:) ligands. The influence of the ligand design, ancillary ligands and geometry of the complexes on the chiroptical and photophysical properties has been highlighted. In the second project, we have prepared novel chiral cyclometalated iridium complexes bearing one or multiple N-[6]helicenyl- benzimidazolylidene ligands.Then, the attention has been focused on monodentate complexes. Thus, in the third project, a chiral copper complex bearing a helicenic-NHC ligand which emits circularly polarized fluorescence was successfully obtained. Finally, chiral monodentate helicenic-NHC gold(I) complexes have been prepared. During this project, the electronic properties (sigma-donating et pi-accepting) of a helicenic-NHC were investigated
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Duan, Gongping. "Design, synthesis, and photophysics and photochromic study of dithienylethene-containing heterocyclic derivatives and N-heterocyclic carbene-ruthenium (II) complexes." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B44248246.
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Holmes, Michael R. II. "The Synthesis And Characterization Of Novel Chiral Gold(I) N-Heterocyclic Carbene Complexes." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1437737871.
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He, Fan. "Transition metal complexes with N-heterocyclic carbene ligands : synthesis and reactivity." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF031/document.
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L’objectif de ce travail est la synthèse de complexes contenant des ligands NHC protiques fonctionnalisés avec un groupement imine dans le but de développer des méthodologies de synthèse donnant accès à des ligands pNHC ainsi que la synthèse des groupes imidazolide anioniques liés par le C et leurs complexes homo et hétéro-dinucléaires. Dans le cas des imidazoles sans groupe fonctionnel, la déprotonation à l’aide de n-butyl lithium a permis l’obtention de (1-aryl-1H-imidazol-2-yl)lithium avec de bons rendements. La réaction de (1-aryl-1H-imidazol-2-yl)lithium avec [Ir(cod)(μ-Cl)]2 ou [Rh(cod)(μ-Cl)]2 a conduit à des complexes dinucléaires bipontés en C2,N3. Dans le cas de l’imidazole possédant une fonctionnalité imine, le complexe de l’Ir(I) lié au N de l’imidazole peut se tautomériser en complexe de l’Ir(I) imine avec un ligand pNHC suite à la réaction d’abstraction du chlorure à température ambiante, alors que la tautomérisation de l’analogue du Rh(I) nécessite une température de 110°C. La déprotonation des complexes de l’Ir(I) et Rh(I) liés par le N de l’imidazole avec addition de [Ir(cod)(μ-Cl)]2 ou de [Rh(cod)(μ-Cl)]2 in situ permet l’obtention de complexes homo et hétéro-dinucléaires. La métallation des sels d’imidazolium fonctionnalisés avec un groupement imine s’est avére être une méthode efficace pour la synthèse de complexes métallés ayant un ligand pNHC et a été étendue des complexes bidentes aux complexes chélatants pNHCThe purpose of this work is the synthesis of complexes containing imine-functionalized protic NHC ligands in order to further develop synthetic methodologies giving access to pNHC, C-bound ‘anionic’ imidazolide, and homo- and heterodinuclear complexes. In the case of imidazoles without functional group, deprotonation with n-butyl lithium afforded (1-aryl-1H-imidazol-2-yl)lithium in good yield. Reaction of (1-aryl-1H-imidazol-2-yl)lithium with [Ir(cod)(μ-Cl)]2 or [Rh(cod)(μ-Cl)]2 yielded a doubly C2,N3-bridged dinuclear complex. In the case of imine-functionalized imidazole, the Ir(I) N-bound imidazole complex can tautomerize to Ir(I) imine-functionalized pNHC complex chloride abstraction at room temperature, while in the Rh(I) analog the tautomerization can be achieved at 110 °C. In situ deprotonation of the N-bound imidazole Ir(I) or Rh(I) complexes, followed by addition of [Ir(cod)(μ-Cl)]2 or [Rh(cod)(μ-Cl)]2 led to the isolation of homo- and heterodinuclear complexes. The metalation of imine-functionalized imidazolium salts is also an effective procedure for synthesis of pNHC metal complexes, and it was extended from bidentate to pincer-type pNHC complexes
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Lesieur, Mathieu. "Cu and Pd complexes of N-heterocyclic carbenes : catalytic applications as single and dual systems." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7999.
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Nowadays, the requirement to design highly valuable compounds is undoubtedly one of the major challenges in the field of organic and organometallic chemistry. The use of the versatile and efficient N-heterocyclic carbenes (NHCs) combined with transition metals represents a key feature in modern organometallic chemistry and homogeneous catalysis. In the course of this thesis, the straightforward design and synthesis of a library of Pd(0) bearing NHC ligands was achieved. Their catalytic performances (Chapter 1) and their phosphorescence properties in solution (Chapter 2) were disclosed. Currently, cross-couplings are some of the most important types of reaction in palladium catalysis. The formation of highly hindered biaryls substrates is one of the main requirements in cross-coupling chemistry. The design and synthesis of a palladium dimer bearing a bulky NHC ligand can fulfil this proposal (Chapter 4). The development of new classes of ligands is a topic of interest. For this reason, normal, abnormal, remote and mesoionic N-heterocyclic carbenes copper complexes were investigated and their reactivity compared in the [3+2] cycloaddition of azides and alkynes (Chapter 7). Air and moisture stable Cu(I)-NHC species have also been compared to their silver analogues for the alkynylation of ketones (Chapter 9). The different reactivity of the two latter organometallic species (Cu and Ag) with ethyldiazoacetate reagent via the formation of carbenes or C-H activated product is presented in Chapter 8. Recently, the development of a bimetallic catalytic system is strongly considered and has high impact. For this reason, two dual catalytic transformations (Pd-NHC and Cu-NHC) were studied for the C-H arylation (Chapter 5) and the synthesis of substituted alkenes products via a relay or cooperative mechanisms (Chapter 6). The isolation of intermediates and mechanistic studies were examined in each of these studies.
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Santoro, Orlando. "Copper(I)-N-heterocyclic carbene (NHC) complexes : synthesis, characterisation and applications in synthesis and catalysis." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/8409.
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The work described herein focuses on the synthesis and characterisation of copper(I) complexes bearing N-heterocyclic carbene (NHC) ligands, their use in catalysis as well as organometallic synthesis and related reaction mechanisms. Two classes of complexes were considered: neutral NHC-Cu(I) species and their cationic analogues. Concerning the former, initial efforts were focused on the development of a general and straightforward synthetic methodology towards complexes of the type [Cu(X)(NHC)] (X = Cl, Br, I). More than 10 NHC-Cu(I) species were synthesised in high yields under mild conditions, in air and using technical grade solvents. These complexes exhibited interesting activity in the catalytic dehydrogenation of formic acid/amine adducts proving in three times more efficiency than the copper salts previously employed in such a reaction. Hydroxide- and tert-butoxide analogues showed to be efficient catalysts in the N-methylation of amines with CO₂ as carbon source, and in the dehydrogenative coupling of silanes and carboxylic acids. Experimental and computational work were carried out in order to elucidate the mechanism of these transformations. Regarding the use of these species in organometallic synthesis, homo- and heteroleptic bis-NHC-Cu(I) complexes were employed as carbene transfer reagents to other transition metals. Aside from well-known cationic gold(I) species, two novel palladium(II) analogues were isolated and fully characterised.
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Deblock, Michael C. "The Synthesis, In Vitro and In Vivo Testing of Silver N-Heterocyclic Carbenes and Imidazolium Complexes." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353951003.
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Jagenbrein, Martin. "Complexes of Bi, Pd, Ir and Hg and N-heterocyclic ligands." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF023.
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L’objectif de cette thèse était la synthèse de nouveaux pro-ligands NHC et de leurs complexes métalliques correspondants, en particulier de l’iridium. La tentative de trouver de nouvelles voies de synthèse de complexes NHC à partir des imidazole-2-thiones correspondants n’a pas donné les résultats attendus.Cependant, il a été possible de préparer des composés de coordination intéressants de ces imidazole-2-thiones : ainsi, un complexe de Bi a été préparé et a pu servir d’agent de transmétallation vers le Pd. De nouveaux proligands NHC de type « pince » et plusieurs de leurs complexes d’iridium ont été préparés. Plusieurs complexes de mercure portant ces ligands ont été synthétisés. De plus, une série de sels d’imidazolium portant des fonctionnalités potentiellement hémilables a été préparée et leur réactivité vis-à-vis de l’iridium étudiéeThe purpose of this thesis was the synthesis of novel pro-ligands to NHCs and their corresponding metal complexes, notably of iridium. While the attempt to find a new pathway to obtain NHC complexes starting from the corresponding imidazole-2-thiones did not yield the expected result, it was possible to obtain interesting coordination compounds from those imidazole-2-thiones themselves:A dinuclear Bi complex was prepared that served as an effective transmetallation agent toward Pd. Novel pincer-type NHC pro-ligands were obtained, and several iridium complexes of their corresponding NHC ligands were prepared. Furthermore, several mercury complexes of these ligands were synthesized. Finally, a series of imidazolium salts bearing potentially hemilabile functionalities were prepared and their reactivity toward Ir was studied
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Brucka, Marta Anna. "N-Heterocyclic carbene complexes of silver, rhodium and iron: structures, dynamics and catalysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3873/.
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The research performed in the framework of this Master Thesis has been directly inspired by the recent work of an organometallic research group led by Professor Maria Cristina Cassani on a topic related to the structures, dynamics and catalytic activity of N-heterocyclic carbene-amide rhodium(I) complexes1. A series of [BocNHCH2CH2ImR]X (R = Me, X = I, 1a’; R = Bz, X = Br, 1b’; R = trityl, X = Cl, 1c’) amide-functionalized imidazolium salts bearing increasingly bulky N-alkyl substituents were synthetized and characterized. Subsequently, these organic precursors were employed in the synthesis of silver(I) complexes as intermediate compounds on a way to rhodium(I) complexes [Rh(NBD)X(NHC)] (NHC = 1-(2-NHBoc-ethyl)-3-R-imidazolin-2-ylidene; X = Cl, R = Me (3a’), R = Bz (3b’), R = trityl (3c’); X = I, R = Me (4a’)).
VT NMR studies of these complexes revealed a restricted rotation barriers about the metal-carbene bond. However, while the rotation barriers calculated for the complexes in which R = Me, Bz (3a’,b’ and 4a) matched the experimental values, this was not true in the trityl case 3c’, where the experimental value was very similar to that obtained for compound 3b’ and much smaller with respect to the calculated one. In addition, the energy barrier derived for 3c’ from line shape simulation showed a strong dependence on the temperature, while the barriers measured for 3a’,b’ did not show this effect. In view of these results and in order to establish the reasons for the previously found inconsistency between calculated and experimental thermodynamic data, the first objective of this master thesis was the preparation of a series of rhodium(I) complexes [Rh(NBD)X(NHC)] (NHC = 1-benzyl-3-R-imidazolin-2-ylidene; X = Cl, R = Me, Bz, trityl, tBu), containing the benzyl substituent as a chiral probe, followed by full characterization. The second objective of this work was to investigate the catalytic activity of the new rhodium compounds in the hydrosilylation of terminal alkynes for comparison purposes with the reported complexes.
Another purpose of this work was to employ the prepared N-heterocyclic ligands in the synthesis of iron(II)-NHC complexes.
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Reade, Steven Peter. "Ruthenium dihydride and hydride fluoride complexes with N-heterocyclic carbenes : a route to C-F bond activation." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507754.
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Maftei, Catalin-Vasile Verfasser], and Matthias [Akademischer Betreuer] [Tamm. "Cytotoxic Metal Complexes With N-Heterocyclic Carbenes Containing 1,2,4-Oxadiazole Substituents / Catalin-Vasile Maftei ; Betreuer: Matthias Tamm." Braunschweig : Technische Universität Braunschweig, 2018. http://d-nb.info/1175816043/34.
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Liu, Ming [Verfasser], and Andreas [Akademischer Betreuer] Schmidt. "Formation of borane adducts and some complexes starting from N-heterocyclic carbenes / Ming Liu ; Betreuer: Andreas Schmidt." Clausthal-Zellerfeld : Technische Universität Clausthal, 2017. http://d-nb.info/1231364963/34.
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Houghton, Jennifer M. "Synthesis and catalytic applications of transition metal complexes of di-N-heterocyclic carbenes incorporating an amine functionality." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421500.
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Gutiérrez, Blanco Ana María. "Tetrametallic (Gold, Iridium and Rhaodium) complexes based on N-Heterocyclic carbenes. From luminescent properties to supramolecular assemblies." Doctoral thesis, Universitat Jaume I, 2021. http://dx.doi.org/10.6035/14104.2021.164087.
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The research carried out in this doctoral thesis can be summarized as the the preparation of different multimetallic complexes containing N-heterocylic carbene (NHC) ligands. In this aim, the main objective is to obtain new poly-NHC-based ligands with extended polyaromatic systems for the preparation of these complexes, which a combination of features that may give access to interesting photophysical and catalytic applications.La investigación llevada a cabo en esta Tesis doctoral puede resumirse como la preparación de diferentes complejos multimetálicos que contienen ligandos carbeno N-heterocíclico (NHC). Con este propósito, el objetivo principal es la obtención de nuevos ligandos basados en poli-NHC con sistemas poliaromáticos extendidos para la preparación de estos complejos, con una combinación de características que pueden dar acceso a aplicaciones fotofísicas y catalíticas muy interesantes.
Programa de Doctorat en Ciències
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Simler, Thomas. "New transition metal complexes with functional N-heterocyclic carbene ligands for molecular activation." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF005.
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Le sujet de cette thèse porte sur l’étude de ligands hybrides incorporant un donneur carbène N-hétérocyclique (NHC). Les ligands phosphine-NHC construits sur le motif m-phénylène ont conduit à des complexes di- ou tétranucléaires d’Ag, Cu, Au et Ir, et à des complexes bimétalliques Ag/Cu et Ag/Ir par transmétallation sélective du site NHC. Dans le cas des ligands phosphino-picoline-NHC (PNC), la transmétallation des sels de Li ou K correspondants a permis d’isoler des complexes « pinceurs » dé-aromatisés du Cr, Fe et Co. La déprotonation du ligand bis(phosphinométhyl)pyridine (PNP) a été examinée, et les ligands dé-aromatisés mono- et bis-anioniques correspondants ont été utilisés dans des réactions de transmétallation vers le Cr(II) et Zr(IV). Différents modes de coordination des ligands dé-aromatisés, notamment une métallation de la position alpha-CHP, ont été observés. La substitution de la phosphine dans PNC par une fonction imine conduit à un ligand hybride « rédox non-innocent »The purpose of this work is the synthesis and study of hybrid and potentially “pincer” ligands featuring an N-heterocyclic carbene (NHC) donor. The phosphine-NHC ligands based on the m-phenylene framework led to di- or tetranuclear Ag, Cu, Au and Ir complexes, and to bimetallic Ag/Cu and Ag/Ir complexes by selective transmetallation of the NHC. With the phosphino-picoline-NHC (PNC) ligands, transmetallation from the corresponding Li or K salts led to dearomatised Cr, Fe and Co “pincer” complexes. Deprotonation of the bis(phosphinomethyl)pyridine (PNP) ligand was also examined. The corresponding dearomatised mono- and bis-anionic ligands were isolated as Li or K salts and further used in transmetallation reactions towards Cr(II) and Zr(IV). Different coordination modes of the dearomatised ligands, including side-arm metallation, were observed. Substitution of the phosphine group in PNC by an imine donor led to a hybrid and “redox non-innocent” ligand
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Kaplan, Hilan. "A General Approach to Cis-Fused Sesquiterpene Quinones and Synthesis, Characterization, and Catalytic Applications of Bis(Imino)-N-Heterocyclic Carbene Complexes of Iron." Thesis, Boston College, 2014. http://hdl.handle.net/2345/3862.
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Thesis advisor: James P. MorkenSesquiterpene quinones are a prolific class of marine natural products that are particularly interesting due to their antibacterial, antiviral, and anti-inhibitory properties. Hundreds of these biologically active molecules are based on decalin frameworks, both cis- as well as trans-fused, however, significantly less synthetic work has focused on targeting the cis-fused series of compounds. In this chapter, progress towards an asymmetric, general route to various sesquiterpene quinones in the cleordane family of natural products will be described. The key steps of the synthesis include a highly convergent and diastereoselective reductive alkylation to forge both the requisite cis-ring fusion well as the all carbon quaternary center, as well as a scandium-catalyzed ring expansion of a 6,5-ring system to deliver the decalin core of the molecule. Additionally, the chapter includes the development and substrate scope of both methodologies utilized in the key complexity building reactions. Iron complexes ligated by bis(imino)pyridine ligands are remarkably active catalysts for a vast range of organic transformations including polymerization, hydrogenation, hydrosilylation, and hydroboration. Whereas much work has been done to probe the importance of the imine-substituents on catalysis, significantly less information is known about the nature of the central pyridine donor. To study the effects of a more donating ligand in which the pyridine is replaced with an N-heterocyclic carbene, a series of novel ligands and their corresponding iron complexes were synthesized and characterized. Whereas imidazole-derived complexes exhibited exclusively bidentate binding modes, 4,5,6-trihydropyrimidylidene-based ligands adopted a tridentate pincer conformation analogous to complexes of bis(imino)pyridines. Bonding in the five-coordinate bis(imino)-N-heterocyclic carbene complex displayed considerably contracted iron-ligand bond distances compared to the analogous bis(imino)pyridine iron complex. The study of physical and electronic structure and bonding in organometallic compounds is a critical for understanding and predicting complex behavior and reactivity. Having synthesized a completely new type of N-heterocyclic carbene (NHC) ligand and the corresponding iron complex, a rigorous study of metal-NHC bonding, magnetism, and redox activity in bis(imino)-NHC (or carbenodiimine, CDI) complexes of iron was carried out. A series of oxidation and reduction reactions on CDI complexes of iron were performed, enabling access to complexes spanning from formally iron(0) to iron (III) oxidation states. A battery of spectroscopic and computational methods, including X-ray crystallography, Mössbauer spectroscopy, SQUID magnetometry, and EPR spectroscopy established the CDI ligand as a redox active chelator. Additionally, a unique iron-carbene interaction was discovered, in which the metal center antiferromagnetically couples with the carbon of the NHC. Intent on developing CDI complexes of iron into practical catalysts for both synthetic organic transformations and polymerization, a series of stoichiometric as well as catalytic reactions were carried out to evaluate the reactivity profile of the novel complexes. Halide atom abstraction generated a new cationic species, which demonstrated different coordination chemistry compared to the bis(imino)pyridine analogue. Furthermore, the addition of a hydride or alkyl lithium reagent to the parent (CDI)FeCl2 species resulted in interesting and unexpected reactivity involving the carbene ligand. Preliminary catalytic hydrogenation experiments established (CDI)FeCl2 as a competent catalyst for the reduction of simple alkenes in the presence of Na(Hg) as a reductant under 80 psi of hydrogen. Additionally, the dichloride species could be readily converted into bis(aryloxide) complexes that were active for the polymerization of lactide to produce poly(lactic acid). The polymerization is very controlled (PDI values are <1.3), and polymers with molecular weights of around 35 kDa can be obtained after 3 hours at room temperature
Thesis (PhD) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Robishaw, Nikki K. "Encapsulating N-heterocyclic carbene complexes into biodegradable nanoparticles and the antimicrobial and antitumor effects." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1530222031725709.
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Hickey, James Laurence. "Synthetic approaches towards gold (I) and silver (I) complexes of functionalised N-heterocyclic carbene ligands." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0090.
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This work focuses on the design and synthesis of Au(I) and Ag(I) complexes from ligand systems that aim to combine both N-heterocyclic carbene (NHC) and phosphine ligand types. A number of synthetic approaches towards both the ligands and the prepared metal complexes have been developed, with a concerted effort on achieving the desired Au(I) or Ag(I) complexes with minimal reaction steps and synthetic style. The thesis body is divided into two main sections. The first section addresses the preparation of suitable ligand precursors of potential Au(I) and Ag(I) complexes in the form of halo- and phosphino-functionalised imidazolium salts. Several series of haloalkylimidazolium salts were prepared that encompass a range of halogens (Cl, Br, I), alkyl substituents (Me, i-Pr, t-Bu, n-Bu), differing alkyl linker length (n = 0-3), and a variety of organic spacers employed to bridge multi-imidazolium moieties. Novel bidentate and multidentate phosphinoalkylimidazolium salts were synthesised from the various haloalkylimidazolium salts, via the substitution of a halide with nucleophilic diphenylphosphide. A new approach towards rare methylene bridged phosphinomethylimidazolium salts was achieved from the reactions of halomethylimidazolium salts with diphenylphosphine. The second section investigates the preparation of Au(I) and Ag(I) complexes from the halo- and phosphino-functionalised imidazolium salts. A series of dicationic 10, 12, and 14-membered metallacyclic Ag(I) complexes were prepared from the bidentate phosphinoalkylimidazolium salts. The dinuclear Ag(I) metallacycles combine two phosphino-functionalised NHC ligands that are bridged by two coordinated Ag(I) ions in an exclusively head-to-head arrangement. A dinuclear Ag(I) metallacycle was investigated for transmetallation potential to a Au(I) complex and found to selectively transmetallate at the Ag(I) coordinated to the NHC ligands to form a bimetallic metallacycle. Unexpected phosphine oxidation of a 10-membered dinuclear Ag(I) metallacycle resulted in complex disproportionation to an isolable and rare silver(I) trimer. Metal-NHC complexes from haloalkylimidazolium salts have not been reported previously, a novel approach to the synthesis of a series of Au(I) complexes from haloalkylimidazolium salts and a respective gold source was developed and is reported herein. Different synthetic approaches towards Au(I) complexes with the phosphinoalkylimidazolium salts explored a variety of ways to generate the NHC from an imidazolium in the presence of the phosphine. A one-pot, high yielding synthesis of a dinuclear Au(I) complex from PPh3 was also devised, with controlled assembly of the complex resulting in a similar head-to-head ligand arrangement to the dinuclear Ag(I) metallacycles. As an aside, a family of mononuclear [Au(R2NHC)2]+ complexes (R = Me, i-Pr, t- Bu, n-Bu, Cy) prepared previously in our research group, was expanded because of the promising antimitochondrial activity shown by [Au(i-Pr2NHC)2]+. Two new [Au(R2NHC)2]+ complexes with simple alkyl chain functionality were prepared with fine-tuned lipophilicity in close proximity to that of [Au(i-Pr2NHC)2]+.
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Stander-Grobler, Elzet. "Carbene ligand and complex design directed towards application in synthesis and homogeneous catalysis." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/1139.
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Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008.Alkylated acetonitrile that forms during the synthesis of the sulfonium salt, [(Me3)2(MeS)S][BF4], is involved in the formation of new , -unsaturated Fischer-type carbene complexes from (CO)5M=C(OMe)CH2Li (M = Cr, W). Metal migration observed when the substitution product obtained from the reaction of the anionic carbene complexes (CO)5M=C(NMe2)CºC¯ (M = Cr, W) with Ph3PAu+ was left in solution, was also kinetically and theoretically investigated. 1H NMR and quantum mechanical (at the B3LYP level of theory) data indicated a complicated mechanism. The a,b-unsaturated Fischer-type carbene complex, (CO)5Cr=C(OMe)CH=C(Me)NH(Me), obtained from the reaction of (CO)5M=C(OMe)CH2¯ with alkylated acetonitrile, was transformed into the new remote one-N, six-membered, carbene ligand (rN1HC6) complex, (CO)5Cr=C(CH=C(Me)N(Me)CH=C(nBu). The carbene ligand unprecedentedly preferred the softer Rh(CO)2Cl moiety to the Cr(CO)5 metal fragment and transferred readily. A new series of remote and abnormal square planar compounds [r/a(NHC)(PPh3)2MCl]CF3SO3 (M = Pd or Ni) was prepared by oxidative substitution. The various positions for metal-carbon bond formation on a pyridine ring to furnish various ligand types i.e. C2 for nN1HC6, C3 for aN1HC6 or C4 for rN1HC6 received attention. The ligands were arranged in increasing order of carbene character, aNHC < nNHC < rNHC and trans influence, nN2HC5 ~ aN1HC6 ~ nN1HC6 < rN1HC6. In competitive situations, oxidative substitution occurred selectively at C4 of the pyridine ring rather than at C2 and on the aromatic ring containing the heteroatom (C4), rather than on an annealed aromatic ring (C7). Crystal and molecular structure determinations confirmed the preferred coordination sites. Quantum mechanical calculations (at the RI-BP86/SV level of theory) indicated that the chosen carbene ligand has a much larger influence than the metal on the BDE of the M-Ccarbene bond; the farther away the N-atom is from the carbene carbon, the stronger the bond. In complexes that also contain additional external nitrogen atoms, e.g. trans-chloro(N-methyl-1,2,4- trihydro-2-dimethylaminepyrid-4-ylidene)bis(triphenylphosphine)palladium(II) triflate and transchloro( N-methyl-1,2,4-trihydro-2-dimethylaminepyrid-4-ylidene)bis(triphenylphosphine)nickel(II) triflate, stabilisation originates from both the nitrogens. 2-Chloro-1-methyl-1H-pyrid-4-ylidenephenylammonium triflate afforded complexes with both remote as well as normal nitrogen atoms. New azole complexes of palladium and nickel with remote heteroatoms were also prepared from N-methyl-4',4'-dimethyl-2'-thiophen-3-chloro-2-yl-4,5-dihydro-oxazole. Employing the compound 1,5-dichloroanthraquinone, the product of a double oxidative substitution on two Pd centra could be isolated but not alkylated. The fact that the chemical shift of the metal bonded carbon in the 13C NMR spectrum can not be used as absolute measure of carbene character, was emphasised in a compound where the heteroatom was situated seven bonds away from the carbon donor. In efforts to synthesise a sulphur-bridged complex that contains carbene ligands, crystals of transdi- iodobis(1,3-dimethyl-imidazoline-2-ylidene)palladium were obtained. Bridged thiolato complexes with N1HC6 ligands were unexpectedly found in the attempt to substitute the halogen on chosen square planar carbene complexes of palladium, widening the application possibilities of N1HC6 ligands in organometallic chemistry beyond that of catalysis. A trinuclear cluster, [(PdPPh3)3(μ-SMe)3]BF4 was isolated as a by-product of these reactions. A series normal and abnormal thiazolylidene complexes of nickel and palladium were prepared by oxidative substitution of the respective 2-, 4- and 5-bromothiazolium salts with M(PPh3)4 (M = Pd or Ni), and unequivocally characterised. In a preliminary catalytic investigation, all the thiazolinium and simple pyridinium derived palladium complexes showed activity in the Suzuki-Miyaura coupling reaction. Little variation in activity in the order a (N next to carbon donor) > n > a (S next to carbon donor) was found for the former series, whereas decreased activity was exhibited in the sequence r > a > n of the latter group. The pyridinium derived complexes showed superior activity to the thiazolinium ones. The rNHC complex, trans-chloro(N-methyl-1,2,4-trihydro-2- dimethylaminepyrid-4-ylidene)bis(triphenylphosphine)palladium(II) triflate, showed similar Suzuki-Miyaura activity to the standard N2HC5 carbene complex precatalyst, trans-chloro[(1,3- dimethyl-imidazol-2-ylidene)triphenylphosphine]palladium(II) triflate.
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Duan, Gongping, and 段公平. "Design, synthesis, and photophysics and photochromic study of dithienylethene-containing heterocyclic derivatives and N-heterocycliccarbene-ruthenium (II) complexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44248246.
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Aksın, Özge Artok Levent. "The activity of silica immobilized palladium N-heterocyclic carbene complexes toward Mizoro-Heck reaction and their characterization/Özge Aksın;thesis advisor Levent Artok." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/kimya/T000341.pdf.
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Thesis (Master)--İzmir Institute of Technology, İzmir, 2005.Keywords: Palladium, Immobilization, Heck Reaction, Palladium-N-Heterocyclic Carbene, Carbon-Carbon Coupling. Includes bibliographical references (leaves. 89-104).
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Au, Ka-man, and 區嘉雯. "Luminescent cyclometalated gold (III) complexes with ancillary N-heterocyclic carbene and alkynyl ligands : from design, synthesis, photophysics to supramolecular assembly and functions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/207995.
Full textAbstract:
A library of luminescent cyclometalated gold(III) complexes containing
various bis-cyclometalating R-C^N^C ligands derived from 2,6-diphenylpyridine
and ancillary alkynyl ligands, [Au(R-C^N^C)(C≡CR’)], has been synthesized.
Some of the complexes have been structurally determined by X-ray
crystallography. These complexes were found to exhibit intense emission in
dichloromethane solution at 298 K, originating from metal-perturbed triplet
intraligand (IL) excited states of the R-C^N^C ligand, with substantial charge
transfer character from the aryl moiety to the pyridyl ring. In the presence of
electron-rich alkynyl ligands, the emission origin could be switched to an
alkynyl-to-cyclometalating ligand ligand-to-ligand charge transfer (LLCT) excited
state. This class of complexes was also demonstrated to show rich
electroluminescence properties as emitters in organic light-emitting devices. In
addition, the supramolecular assembly of this class of complexes has also been
revealed in gelation studies.
N-Heterocyclic carbenes have been incorporated into the gold(III) metal
center to prepare a series of luminescent mononuclear and dinuclear gold(III)
complexes, [{Au(C^N^C)}n(NHC)](PF6)n and [{Au(tBuC^N^CtBu)}n(NHC)]-
(PF6)n
(n = 1, 2). The X-ray crystal structures of most of the complexes have been
determined. The emissions of these complexes were assigned to originate from the
metal-perturbed intraligand excited state of the bis-cyclometalating ligand. One of
the C2-bridged dinuclear complexes was found to exhibit two distinct reduction
couples, tentatively correlated to the presence of significant intramolecular π-π
interaction in the complex.
Two novel series of luminescent mononuclear alkynylgold(III) complexes,
[Au(C^N)(C≡CR)2] (HC^N = 2-phenylpyridine (Hppy) and derivatives) and
[Au(C^N^N)(C≡CR)]PF6 (HC^N^N = 6-phenyl-2,2’-bipyridine and derivatives),
have been synthesized. Some of the X-ray crystal structures have been determined.
The former class of complexes with bidentate C^N ligands has been observed to
show tunable emission spanning across the visible spectrum from 462 to 697 nm.
With the exception of [Au(ppy)(C≡C-C6H4-NH2-p)2] which showed a low-energy
band originated from a 3LLCT [π(C≡C-C6H4-NH2)→π*(C^N)] excited state, all
complexes exhibited vibronic-structured emission bands originated from the
intraligand transition of the cyclometalating C^N ligand in dichloromethane
solution at 298 K. On the other hand, most of the complexes with the tridentate
C^N^N-type ligand have been observed to exhibit vibronic-structured emission
bands attributed to the intraligand transition of the C^N^N ligand in
low-temperature butyronitrile glass.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
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Ai, Pengfei. "Synthesis and reactivity of metal complexes containing functionalized N-heterocyclic carbene ligands for catalytic applications." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF025/document.
Full textAbstract:
L’objectif de ce travail fut la synthèse de ligands fonctionnels de type N,N'-diphosphanyl-NHC (NHC = carbènes N-hétérocycliques) et l’étude de leur chimie de coordination. La synthèse du nouveau ligand tridentate, stable et rigide, N,N'-diphosphanyl-imidazol-2-ylidene a permis des études expérimentales et théoriques et l’accès à des complexes mono-, di-, tri-, penta-, et hexanucléaires des métaux du groupe 11 (Cu, Ag et Au) originaux et aux propriétés structurales uniques. Les complexes mono- et dinucléaires avec un ou deux atomes de phosphore libres ont permis d’accéder à des complexes hétérotrinucléaires à interactions d10-d10 qui sont luminescents. La transmétallation partielle ou totale des complexes homotrinucléaires de Cu ou d’Ag avec des réactifs contenant du Pd(0) ont conduit à des complexes hétérotrinucléaires à interactions d10-d10. En plus de son comportement pontant, ce ligand peut se agir en chélate dans des complexes du palladium et du chrome. Dans le cas du Cr(III), ils montrent une activité catalytique en oligomérisation de l’éthylène supérieure à celle des complexes du Cr(II) et conduisent principalement à des oligomèresThe purpose of this work was the synthesis of N,N'-diphosphanyl-functionalized NHC ligands andtheir coordination chemistry. The novel stable and rigid tridentate N,N'-diphosphanyl-imidazol-2-ylidene was synthesized and experimental and computational information on its stability weregained. It served as a unique platform for the synthesis of novel mono-, di-, tri-, penta-, hexanuclear complexes with the coinage metals (Cu, Ag and Au), exhibiting rare structural features. The mono- and dinuclear complexes with one or two dangling P-donors provided rational access to heterotrinuclear complexes. All these coinage metal complexes have short metal-metalseparations, indicating the presence of d10-d10 interactions, and display excellent luminescentproperties. Partial or complete transmetallation of the homotrinuclear Cu or Ag complexes withPd(0) precursors led to hetero-trinuclear complexes with d10-d10 interactions. In addition to itsbridging behavior, this ligand also showed its chelating behavior in Pd or Cr(III) complexes. Thelatter displayed superior performance in ethylene oligomerization than the Cr(II) complexes andgave mostly oligomers
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Herrmann, Dirk [Verfasser], and Robert [Akademischer Betreuer] Wolf. "Synthesis, Characterization, and Reactivity of Transition Metal Complexes Stabilized by Naphthalene and Naphthyl-substituted N-heterocyclic Carbenes / Dirk Herrmann ; Betreuer: Robert Wolf." Regensburg : Universitätsbibliothek Regensburg, 2019. http://d-nb.info/1196873437/34.
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Knapp, Amanda R. "Antimicrobial and Antitumor Properties of Free and Poly(Ethylene Glycol)-Poly(Lactic Acid) Encapsulated Silver N-Heterocyclic Carbene Complexes." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1309211795.
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May, Tricia Lee. "Copper-Based N-Heterocyclic Carbene Complexes for Catalytic Enantioselective Conjugate Additions of Alkyl-, Aryl- and Vinyl-Based Nucleophiles to Form All-Carbon Quaternary Stereogenic Centers." Thesis, Boston College, 2011. http://hdl.handle.net/2345/2650.
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Thesis advisor: Amir H. HoveydaChapter 1 Enantioselective Conjugate Additions of Carbon Nucleophiles to Activated Olefins: Preparation of Enantioenriched Compounds Containing All-Carbon Quaternary Stereogenic Centers. Methods for enantioselective conjugate addition of nucleophiles to activated olefins generating products containing all-carbon quaternary stereogenic centers are critically reviewed. Enantioselective conjugate addition has been shown to be a powerful and concise approach to construct carbon-carbon bonds to prepare compounds containing sterically hindered stereogenic centers and has seen great advances in the past several years. Owing to the difficult nature of additions to relatively unreactive conjugate acceptors, compared to additions generating tertiary stereogenic centers, and construction of a sterically-hindered bond, in many cases, new and active catalysts had to be developed. The review discusses the areas where significant advances have been made as well as current limitations and future outlook. Chapter 2 Development of New and Active Catalysts for Cu-Catalyzed Enantioselective Conjugate Addition of Alkyl- and Arylzinc Reagent. Through development of new chiral catalysts, we have found an active and enantiodiscriminating bidentate, sulfonate-containing NHC-Cu catalyst that effects enantioselective conjugate addition of alkyl- and arylzinc reagents on notoriously difficult trisubstituted cyclic enones. Products are prepared with high levels of selectivity and participate in a variety of further functionalizations. The enantioselective additions are efficient and practical, not requiring rigorously anhydrous or oxygen-free conditions. Chapter 3 Cu-Catalyzed Enantioselective Conjugate Addition of Alkyl- and Arylaluminum Reagents to Trisubstituted Enones. Outlined in this chapter is the first effective solution for Cu-catalyzed enantioselective addition of alkyl and aryl nucleophiles to trisubstituted cyclopentenones generating products bearing a β-all-carbon quaternary stereogenic center. Products are obtained in up to 97% yield and 99:1 er, only requiring 5 mol % of an in situ generated Cu-NHC catalyst. The methodology was highlighted as one of the key steps in the total synthesis of clavirolide C. Not only five-membered rings, but six- and seven-membered rings serve as proficient partners in the enantioselective process. Moreover, in cases for the enantioselective aryl addition, in situ prepared Me2AlAr can be used without purification, filtration, or isolation, only requiring the corresponding aryl halides. The additions have also been extended to trisubstituted unsaturated lactones and chromones. Chapter 4 Cu-Catalyzed Enantioselective Conjugate Addition of Vinylaluminum Reagents to Cyclic Trisubstituted Enones. An enantioselective protocol for the formation of β,β-disubstituted cyclic ketones containing a synthetically versatile vinylsilane is disclosed. Enantioselective conjugate addition of in situ prepared silyl-substituted vinylaluminum reagents to β,β-unsaturated ketones promoted by 5 mol % of chiral Cu-NHC complexes delivers desired products with high efficiency (up to 95% yield after purification) and enantioselectivities (up to >98:<2 er). Several functionalizations utilizing the vinylsilanes, vicinal to an all-carbon quaternary stereogenic center, are shown, including an oxidative rearrangement, vinyl iodide formation and protodesilylation, accessing products not previously attainable. Furthermore, the enantioselective protocol is demonstrated as the key transformation in the total synthesis of riccardiphenol B
Thesis (PhD) — Boston College, 2011
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Hameury, Sophie. "Oxygen-functionalized NHC ligands and their nickel(II), silver(I) and palladium(II) complexes." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF010.
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L’objectif de cette thèse portait sur la synthèse de complexes portant un ligand NHC associé à une fonction oxygénée et à leur application en catalyse d’oligomérisation de l’éthylène. Dans le but de synthétiser des complexes avec des ligands NHCalcool, les complexes d’argent correspondants ont été synthétisés et utilisés en transmétallation. Aucun résultat concluant n’a pu être obtenu avec le nickel à cause de l’acidité du proton alcoolique. Mais un ligand NHC-alcoolate a pu être obtenu par déprotonation directe du pro-ligand avec une base forte. Il fut alors possible d’accéder à des complexes de nickel polynucléaires, certains incorporant dans leur structure des cations lithium provenant de la base utilisée. Par comparaison, des complexes de palladium ont été synthétisés avec des NHCs-alcool ou -alcoolate par réaction des pro-ligands avec Pd(acac)2 suivie de réactions acido-basiques. Etant donné la difficulté d’obtention des complexes de nickel avec des ligands NHC-alcool, la fonction éther a été étudiée. Les complexes résultants ont été testés en oligomérisation de l’éthylèneThe purpose of this work was the synthesis of complexes bearing O-functionalized NHC ligands in order to test their catalytic properties in ethylene oligomerization. In order to have access to alcohol-functionalized complexes, the corresponding silver complexes were synthesized for transmetallation purpose. Whereas no concluding results were obtained with the alcohol function in association with nickel, it was possible to access an alcoholate-functionalized NHC ligand by deprotonation of the corresponding pro-ligand. Thus, polynuclear nickel complexes were prepared, some of them included in their structure a lithium cation originating from the base. For comparison, alcohol- and alcoholate-functionalized NHC palladium complexes were synthesized by direct reaction of the pro-ligand with Pd(acac)2 followed by acidobasic reactions. Because of the complexity of the chemistry of NHC-alcohol ligands associated with nickel, the ether functionality was explored. A library of nickel complexes was synthesized and tested in the catalytic ethylene oligomerization
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Zou, Taotao, and 邹滔滔. "Anti-cancer N-heterocyclic carbene complexes of gold(III), gold(I) and platinum(II) : thiol "switch-on" fluorescent probes, thioredoxin reductase inhibitors and endoplasmic reticulum targeting agents." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/208614.
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Martínez, Agramunt Víctor. "Nickel and palladium supramolecular organometallic complexes based on NHC-ligands with polyaromatic moieties for host-guest chemistry studies." Doctoral thesis, Universitat Jaume I, 2020. http://dx.doi.org/10.6035/14104.2020.366143.
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Se ha obtenido una nueva familia de cuatro Complejos Organometálicos Supramoleculares (SOCs) basados en pireno. Dentro de los cuales se ha desarrollado un nuevo receptor de PAH, capaz de discernir entre los diferentes PAH en función de su forma, tamaño, y número de electrones-pi. Hemos desarrollado una estrategia eficiente para la extracción de PAH, que son compuestos tóxicos y carcinogénicos, en disolventes orgánicos. Paralelamente, se han obtenido dos receptores de fulereno, capaces de adaptar su tamaño a la forma del fulereno. Debido a la mayor afinidad respecto a un fulereno específico, mostramos un potencial nuevo método de purificación de fulerenos. Describimos el primer sistema host-guest utilizado como fotosensibilidazor en la generación de oxígeno singlete. Este SOC con fulereno atrapado, fue capaz de oxidar una gran variedad de alquenos utilizando el oxígeno singlete generado a partir de aire a presión atmosférica y luz visible. Finalmente se encapsularon multiples guests.Three nickel-based and one palladium-based supramolecular organometallic cages have been prepared. These four cages are based on a N-heterocyclic carbene ligand with a pyrene tag, that has been key in the subsequent applications of the cage together with the inner cavity. By pi-stacking interactions, it has been possible to encapsulate both polycylic aromatic hydrocarbons and fullerenes. The interest on first group of compounds is based on their accurate toxicity while the fullerenes are interesting due to their added value. It was possible to extract the first group of molecules from an organic media through the encapsulation inside the supramolecular cages. The host-guest adduct formed with fullerenes encapsulated inside the palladium cage was used as photocatalyst of aromatic, cyclic and acyclic substrates via singlet oxygen generation. The same palladium cage was used as receptor for multiple stacks of polyaromatic compounds.
Programa de Doctorat en Ciències
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Ren, Xiaoyu. "Synthèse et réactivité de complexes métalliques porteurs de ligands carbéniques N-hétérocycliques fonctionnels." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF081/document.
Full textAbstract:
Des ligands hydrides potentiellement bidentes (possédant un donneur N-hétérocyclique (NHC) associé à un groupement donneur éther ou amine) ainsi que des ligands tritopiques de type pinceur (possédant un groupement (NHC) flanqué de deux types de donneurs azotés différents Nimine et Namine) ont été préparés et utilisés pour la coordination de métaux de transition tels que le Ni, Cr, Cu et Ir. L’influence de la longueur de la chaine alkylée -(CH2)2- ou -(CH2)3- reliant le groupe éther ou amine au groupe hétérocyclique (NHC) a été examinée. Dans le but d’accéder aux complexes des métaux de transition différentes méthodologies ont été adoptées : a) déprotonation préalable du sel d’imidazolium suivie de l’addition des précurseurs métalliques correspondants ; b) transmétallation à partir des complexes (NHC) de l’argent correspondants ; c) réaction d’addition oxydante des sels d’imidazolium ou de leurs sels protonés avec du Ni(0). Une série de complexes du Ni(II) et du Cr(III) a été testée dans la réaction catalytique d’oligomérisation de l’éthylènePotentially bidentate hybrid ligands (containing a NHC donor associated with an ether or an amine) and tridentate NCN pincer-type ligands (containing a central NHC donor flancked by two chemically-different nitrogen donors (Nimine and Namine)) have been prepared and used for coordination to transition metals, such as Ni, Cr, Cu, Ir. The influence of the length of the alkyl chain, -(CH2)2- or -(CH2)3- connecting the ether or the amine group to the heterocycle NHC was examined. In order to have access to the transition metal complexes, several methodologies were adopted: a) deprotonation of the corresponding imidazolium salts followed by addition of transition metal precursors; b) transmetalation from NHC silver complexes; c) oxidative-addition reaction of Ni(0) with imidazolium salts or the corresponding protonated salts. A series of Ni(II), Cr(III) complexes were tested in the catalytic ethylene oligomerization reaction