Video Experimental Relacionado
Updated: Jun 13, 2026
![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
09:12
[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
Exploraciones computacionales de los mecanismos y las selectividades dirigidas por ligandos de las reacciones de tipo
Gavin O Jones1, Peng Liu, K N Houk
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|April 15, 2010
Resumen
Los estudios computacionales revelan que la elección del ligando dicta la selectividad en las reacciones de acoplamiento de tipo Ullmann catalizadas por cobre. El ligando específico influye en si se produce la arilación N- u O, principalmente durante el paso de activación del haluro de arilo.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química computacional es la química computacional.
- La catálisis por catálisis.
Sus antecedentes:
- Las reacciones de acoplamiento tipo Ullmann son cruciales para la formación de enlaces C-N y C-O.
- La selección de ligandos tiene un impacto significativo en la selectividad y la eficiencia de las reacciones de acoplamiento cruzado catalizadas por cobre.
- Trabajos experimentales anteriores destacaron selectividades dirigidas por ligandos en la N- versus O-arilación utilizando complejos específicos de cobre (I).
Objetivo del estudio:
- Para investigar computacionalmente el origen de las selectividades dirigidas por ligandos en las reacciones de acoplamiento de tipo Ullmann.
- Esclarecer los mecanismos que rigen la N- versus O-arilación por complejos beta-diketona- y 1,10-fenantrolina-ligados Cu (I).
- Determinar los factores que controlan la selectividad en las reacciones que involucran metanol, metilamina e iodobenzeno.
Principales métodos:
- Los cálculos de la Teoría Funcional de Densidad (DFT) se emplearon para estudiar las vías de reacción.
- Los cálculos se centraron tanto en la formación de nucleófilos como en los pasos de activación del haluro de arilo.
- Se utilizaron múltiples funciones DFT para garantizar la solidez de los hallazgos.
Principales resultados:
- La selectividad dirigida por ligandos surge de la etapa de activación del haluro de arilo, no de la formación inicial del complejo.
- El mecanismo de reacción (transferencia de un solo electrón [SET] o transferencia de átomo de yodo [IAT]) depende de las propiedades del ligando y del nucleófilo.
- Los ligandos beta-dicatona favorecen la N-arilación a través de los mecanismos SET, mientras que los ligandos fenantrolina favorecen la O-arilación a través de los mecanismos IAT.
Conclusiones:
- Los estudios computacionales de DFT explican con precisión las selectividades de N- versus O-arilación experimentalmente observadas en acoplamientos de tipo Ullmann.
- Las propiedades electrónicas del ligando y el nucleófilo dictan la vía de reacción dominante (SET o IAT).
- La comprensión de estos detalles mecánicos permite el diseño racional de catalizadores para la formación selectiva de enlaces C-N y C-O.
Más Videos Relacionados
11:04Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides
Published on: September 7, 2019
08:56Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
Published on: November 30, 2022
Videos de Conceptos Relacionados
01:07Ladder Diagrams: Complexation Equilibria
Ladder diagrams are useful for evaluating equilibria involving metal-ligand complexes. The vertical scale of the ladder diagram represents the concentration of unreacted or free ligand, pL. The horizontal lines on the scale depict the log of stepwise formation constants for metal-ligand complexes and indicate the dominant species in all the regions.
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
00:56Extraction: Advanced Methods
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is formed in...
00:49Ligand Binding and Linkage
Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...
01:22Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
01:26Limitations of Friedel–Crafts Reactions
Several restrictions limit the use of Friedel–Crafts reactions. First, the halogen in the alkyl halide must be attached to an sp3-hybridized carbon for the Friedel–Crafts reactions to occur. Vinyl or aryl halides do not react since the carbocations formed are unstable under the reaction conditions. Second, Friedel–Crafts alkylation is susceptible to carbocation rearrangement, and the major products obtained have a rearranged carbon skeleton. In contrast, the acylium ion is stabilized by...
01:13Introduction to Mechanisms of Enzyme Catalysis
For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...