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Showing 1 to 20 of 168 for “"carbene"”.
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Mechanistic studies in carbene and polyurethane chemistry
<p>The chemistry of benzylchlorocarbene was investigated through both theory and experiment. Photolysis of a phenanthrene-based precursor in an NMR tube gave evidence for isomeric beta-chlorostyrenes but not the alpha-isomer. Computations showed that insertion into the aromatic ring should have a …
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Synthesis and application of rhodium(I) Fischer carbene complexes
In this study, novel rhodium(I) carbene complexes were synthesized and fully characterized via a carbene ligand transfer methodology from Group 6 Fischer carbene complex precursors and subsequent ligand modification. The classic Fischer route was followed towards the isolation of mono- and …
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Coinage Metal Chalcogenide Clusters with N-Heterocyclic Carbene Ancillary Ligands
… group 11 – group 16 clusters with N-heterocyclic carbene (NHC) ligands. The clusters were prepared from reactive group 11 trimethylsilylchalcogenolate reagents (NHC-M-ESiMe3; M = Cu, Au; E = S, Se, Te) by silane deprotection reactions with phosphine- or phosphite-solubilized group 11 acetates …
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N-heterocyclic Carbene Synthesis Towards Self-Assembled Monolayers on Gold
… strength and surface stability of n heterocyclic carbenes (NHCs) to a gold substrate. Here in we report the synthesis and modification of gold surfaces with NHCs containing unique functionality. Chemical synthesis was characterized using nuclear magnetic resonance spectroscopy techniques and SAM …
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Spectroscopic Studies of Excited States in Carbene-Metal-Amide Emitters
… in OLEDs is a very active area of research. Carbene-Metal-Amides (CMAs) are a recent class of organometallic semiconductors with proposed applications in high-performance OLEDs. Fast triplet harvesting in CMAs occurs through thermally activated delayed fluorescence (TADF). In contrast to …
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Fischer and N-heterocyclic carbene complexes of Group (VII) transition metals
… application of Fischer- and N-heterocyclic carbene (NHCs) complexes of the group VII transition metals were investigated. By using density function theory calculations, the structural and electronic parameters could be elucidated and the fundamental bonding interactions between the carbene …
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Synthetic and catalytic studies of Group 11 N-heterocyclic carbene complexes
… 11 metal complexes, supported by N-heterocyclic carbene (NHC) ligands. The NHC ligand was found to stabilize monomeric, terminal fluoride complexes of copper, silver and gold, the last representing the first isolable gold(I) fluoride. These complexes were shown to be reactive synthons for new …
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Synthesis, Activation and Catalytic Activity of N-Heterocyclic Carbene Bearing Palladium Catalysts
… of (NHC)Pd(II) complexes (NHC = N-heterocyclic carbene) are described. A variety of architectures and precursors have been employed to lead to numerous air- and moisture-stable complexes. The use of those complexes as pre-catalysts in cross-coupling (Suzuki- Miyaura, Buchwald-Hartwig) and …
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Synthetic investigation of Mn(I) and Re(I) N-heterocyclic carbene complexes
… to be unsuccessful as isolation of the free carbene should rather be performed in an argon filled glove box under extreme inert conditions. By way of further investigation the ylidene was prepared by in situ methods and then quenched with the metal substrate. Different bases for deprotonation …
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A New 2,1,3-Benzothiadiazole-Fused N-Heterocyclic Carbene and Its Metal Complexes
<p>In the last few decades, N-heterocyclic carbenes (NHCs) have emerged as a powerful class of carbon-based ligands. Owing to their unique electronic and steric properties, they have been incorporated in a large variety of catalytically active metal complexes. One of the strategies that have been …
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Development and exploration of Schiff base ruthenium carbene catalysts for olefin metathesis
… the development of new NHCs (N-Heterocyclic Carbene) for the 2nd generation Grubbs catalysts and a detailed investigation of secondary metathesis events. The Schiff base substituted second generation Grubbs catalysts were synthesized, proving a previous synthesis was incorrect. The new …
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The Utilization of Carbene Catalysis and Different Synthetic Strategies for Sydnone Construction
… the synthesis of benzoin was conducted using carbene precatalyst bis(amino)cyclopropenylidene (BAC-H) with multiple different bases that are used in literature. It was determined that the combination of bases sodium hydride and KHMDS provided moderate yields of benzoin. Further optimization …
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Scanning Probe Study of N-Heterocyclic Carbene Self-Assembly on Coinage Metal Surfaces
… surface anchor. More recently, N-heterocyclic carbenes (NHCs) have gained interest due to their increased oxidative and thermal robustness relative to the thiol. Since the emergence of NHCs in surface science, several key insights into how their structure relates to their adsorption motif have …
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Synthesis of Well-Defined N-Heterocyclic Carbene (NHC) Complexes of Late Transition Metals
N-heterocyclic carbenes (NHCs) have emerged as appropriate replacements for phosphines to synthesized highly active metal complexes in homogeneous catalysis. The advantages of NHCs over phosphines include ease of handling, minimal toxicity and powerful electron donating properties. They bind …
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Development of Cobalt and Nickel N-Heterocyclic Carbene Complexes for Cross-Coupling Reactions
Cross-coupling, which relies on the use of transition metals, is among the most utilized chemical means of establishing carbon-carbon or carbon-heteteroatom bonds between appropriately functionalized sp, sp2, or sp3 centres. However, most cross-coupling reactions rely on the use of palladium to …
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Studies toward Augmented Carbene/Alkyne Cascade Reactions and Ruthenium Catalysts for Propargylic Substition
… materials. Then the reaction goes through metal-carbene and alkyne insertion, and finally C-H insertion or alkyl migration. Because of ring-strain and steric effects, a cyclic syn-alkynyl diazoacetate approach underwent direct C-H insertion. A linear di-alkynyl diazoacetate approach underwent a …
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(N-heterocyclic-carbene)Copper(I)-catalyzed carbon-carbon bond formation using carbon dioxide
This thesis presents work towards the development of a new catalytic C-C bond forming reaction. Alkynes and olefins insert into [(IPr)CuH]2 (IPr = N,N-bis-(2,6-diisopropylphenyl)-1,3-imidazol-2-ylidene) to give copper vinyl and copper alkyl complexes. These copper complexes insert CO2 into the Cu-C …
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On the Colour Tuning and Stability of Carbene-Metal-Amide Organic Light-Emitting Diodes
… classes of emitters. One such possibility are carbene-metal-amides (CMAs). CMAs are a family of charge transfer type photoemitters which luminescence through a thermally activated delayed fluorescence mechanism. CMAs have been previously incorporated into highly efficient green OLEDs. In …
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NEW GO- AND RGO-BASED MORALS AND CARBENE-FUNCTIONALIZED GOLD NANOPARTICLES FOR HETEROGENEOUSLY CATALYZED REDUCTIONS
… investigated consists of N heterocyclic carbene (NHC)-functionalized gold nanoparticles. Gold nanoparticles (AuNPs) are widely recognized for their unique optical, electronic, and catalytic properties, which have enabled applications ranging from sensing and biomedicine to fine chemical …
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Synthesis of alkyl- and poly(ethylene)glycol linked bis-dioxocyclams from bis-chromium carbene complexes
Alkyl-linked bis-chromium carbene complexes have been prepared via deprotonation and α-alkylation of (methoxy)(methyl) chromium carbene complexes using l,n-bis-triflates as electrophiles. These bis-carbene complexes were then photolyzed with N-protected imidazolines to give protected bis-azapenams. …
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