The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Bo Liedberg - One of the best experts on this subject based on the ideXlab platform.
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Tricyclohexylphosphine adsorbed on rhodium
Langmuir, 1998Co-Authors: Kajsa Uvdal, Ingmar Persson, Hans Kariis, Gunnar Westermark, Mikael Wirde, U Gelius, Bo LiedbergAbstract:Tricyclohexylphosphine (TCHP) adsorbates on rhodium, prepared both from solution and by sublimation in UHV are studied by X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IRAS), and temperature-programmed desorption (TP
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Tricyclohexylphosphine adsorbed on gold
Langmuir, 1995Co-Authors: Kajsa Uvdal, Ingmar Persson, Bo LiedbergAbstract:Tricyclohexylphosphine adsorbates on gold, as well as multilayer films of Tricyclohexylphosphine, are investigated by X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IRAS). Molecular orientation and molecular surface interaction for adsorbates prepared from solution are studied, using the multilayer films as references. Since phosphines are easily oxidized in contact with air, the reference, made from a pressed pellet of the starting material, consists of a considerable amount of oxidized Tricyclohexylphosphine. Therefore an oxygen-free reference would also be desirable. Such a reference of a Tricyclohexylphosphine multilayer was obtained by fractionating Tricyclohexylphosphine from Tricyclohexylphosphine oxide by a sublimation process under ultrahigh vacuum. The results from both a pressed pellet of the starting material and an evaporated Tricyclohexylphosphine multilayer are compared with the results from the adsorbate. When Tricyclohexylphosphine is adsorbed from solution onto gold, there is a preferential adsorption of the unoxidized Tricyclohexylphosphine. The molecular structure is intact during adsorption and the molecules are oriented with the phosphine atoms close to the surface. The chemical shift of the P(2p 3/2 ) binding energy during adsorption indicates an electron donation from the adsorbate to the meta
Yu Zhu - One of the best experts on this subject based on the ideXlab platform.
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Tricyclohexylphosphine cyclopalladated ferrocenylimine complexes synthesis crystal structures and application in suzuki and heck reactions
Dalton Transactions, 2006Co-Authors: Junfang Gong, Sufang Yue, Yu ZhuAbstract:A series of novel Tricyclohexylphosphine (PCy3)-cyclopalladated ferrocenylimine complexes 2c–2g have been easily synthesized. These new palladacycles are thermally stable and are not sensitive to air and moisture. Their detailed structures have been determined by single-crystal X-ray analysis and six different types of intermolecular hydrogen bonds are found to be existed in the crystals of these complexes. The use of 2c–2g as catalysts for Suzuki and Heck reactions was examined. They were found to be very efficient for the Suzuki reaction of aryl chlorides with phenylboronic acid. Typically, using 0.1 mol% of catalyst in the presence of 1.5 equivalent of Cs2CO3 as base in dioxane at 100 °C provided coupled products in excellent yields. These complexes also displayed good activity in the Heck reaction of a range of aryl bromides with acrylic acid ethyl ester although they were not particularly useful for the activation of aryl chlorides.
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efficient suzuki coupling of aryl chlorides catalyzed by Tricyclohexylphosphine adducts of cyclopalladated ferrocenylimines
Journal of Organometallic Chemistry, 2005Co-Authors: Junfang Gong, Guangyu Liu, Yu ZhuAbstract:Abstract The air and moisture stable Tricyclohexylphosphine (PCy3) adducts of dimeric cyclopalladated ferrocenylimines 5 and 6 have been easily synthesized and successfully used in palladium-catalyzed Suzuki cross-coupling of aryl chlorides. Using 0.1 mol% of 6 in the presence of 2 equivalent of Cs2CO3 as base in dioxane at 100 °C provided coupled products in excellent yields in the reaction of non-activated and deactivated aryl chlorides with phenylboronic acid. For activated chlorides such as 4-chloronitrobenzene and 4-chloroacetophenone, the catalyst loadings could be lowered to 0.01 mol% without loss of activity.
Kajsa Uvdal - One of the best experts on this subject based on the ideXlab platform.
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thermal reduction of activation energy of Tricyclohexylphosphine on a rhodium crystal surface
Journal of Chemical Physics, 2001Co-Authors: Almas F Sadreev, Kajsa Uvdal, Yurii V Sukhinin, Anna PohlAbstract:The activation energy of desorption of molecules adsorbed on crystal surfaces is defined by the interaction potential. This potential is reduced for finite temperature because of phonon excitations of the crystal surface. Moreover, rotations of molecules relative to the crystal surface contribute to the thermal reduction of the activation energy. As an application we consider organic phosphines on a rhodium surface. We interpolate the interaction by the Morse potential with parameters fitted to data obtained by density functional theory. The theoretical results are compared to temperature-programmed desorption experiments of Tricyclohexylphosphine adsorbates on the rhodium crystal surface. The activation energy of desorption of the monolayers are calculated from temperature programmed desorption studies using the Redhead equation.
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Tricyclohexylphosphine adsorbed on rhodium
Langmuir, 1998Co-Authors: Kajsa Uvdal, Ingmar Persson, Hans Kariis, Gunnar Westermark, Mikael Wirde, U Gelius, Bo LiedbergAbstract:Tricyclohexylphosphine (TCHP) adsorbates on rhodium, prepared both from solution and by sublimation in UHV are studied by X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IRAS), and temperature-programmed desorption (TP
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Tricyclohexylphosphine adsorbed on gold
Langmuir, 1995Co-Authors: Kajsa Uvdal, Ingmar Persson, Bo LiedbergAbstract:Tricyclohexylphosphine adsorbates on gold, as well as multilayer films of Tricyclohexylphosphine, are investigated by X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IRAS). Molecular orientation and molecular surface interaction for adsorbates prepared from solution are studied, using the multilayer films as references. Since phosphines are easily oxidized in contact with air, the reference, made from a pressed pellet of the starting material, consists of a considerable amount of oxidized Tricyclohexylphosphine. Therefore an oxygen-free reference would also be desirable. Such a reference of a Tricyclohexylphosphine multilayer was obtained by fractionating Tricyclohexylphosphine from Tricyclohexylphosphine oxide by a sublimation process under ultrahigh vacuum. The results from both a pressed pellet of the starting material and an evaporated Tricyclohexylphosphine multilayer are compared with the results from the adsorbate. When Tricyclohexylphosphine is adsorbed from solution onto gold, there is a preferential adsorption of the unoxidized Tricyclohexylphosphine. The molecular structure is intact during adsorption and the molecules are oriented with the phosphine atoms close to the surface. The chemical shift of the P(2p 3/2 ) binding energy during adsorption indicates an electron donation from the adsorbate to the meta
Jose E Cortesfigueroa - One of the best experts on this subject based on the ideXlab platform.
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mechanism of piperidine pip dissociation from cis Tricyclohexylphosphine pip tetracarbonyl molybdenum 0
Journal of Coordination Chemistry, 1997Co-Authors: Jose E Cortesfigueroa, Lara Santiago, Madeline Leon, Marilyn P De JesusAbstract:Abstract Piperidine (pip) dissociates from cis-η1-(P(cy)3)(pip)Mo(CO)4 (cy=cyclohexyl) to produce cis-η2-(P(cy)3)Mo(CO)4, where P(cy)3 forms a five-membered ring bonded to molybdenum via phosphorus at one end and hydrogen (agostic bond) at the other end. Results from kinetics studies suggest that loss of pip from cis-η1-(P(cy)3)(pip)Mo(CO)4 takes place via a dissociative mechanism, where the electronically unsaturated species cis-η1-(P(cy)3)Mo(CO)4 is formed during the reaction. This intermediate is very reactive and is concurrently attacked by pip to produce the parent complex cis-η1-(P(cy)3)(pip)Mo(CO)4 and by cy from the coordinated P(cy)3 to give the product of the reaction.
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displacement of piperidine pip from cis Tricyclohexylphosphine pip tetracarbonyl tungsten 0
Journal of Coordination Chemistry, 1995Co-Authors: Omar Laboy, Elsie I Paresmatos, Jose E CortesfigueroaAbstract:Abstract Displacement of piperidine (pip) from cis-η1-(P(cy)3)(pip)W(CO)4 (cy = cyclohexyl) to produce η2-(P(cy)3(pip)W(H)(CO)4 is biphasic. Plots of absorbance (λ = 400 nm) vs. time show two consecutive first order reactions. The first reaction involves dissociation of pip to produce the chelate complex η2-(P(cy)3)W(CO)4, where P(cy)3 forms a five-membered ring bonded to tungsten via phosphorus at one end and via hydrogen (agostic bond) at the other end. The second reaction involves intramolecular oxidative addition (cyclometalation) of cy to produce η2-(P(cy)3)W(H)(CO)4. Results from kinetic studies suggest that departure of pip from cis-η1-(P(cy)3)(pip)W(CO)4 is assisted by the solvent via a dissociative interchange mechanism, whereas the second part of the biphasic process is best described as an associative interchange mechanism.
Junfang Gong - One of the best experts on this subject based on the ideXlab platform.
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catalysis of the coupling reaction of aryl chlorides with bis pinacolato diboron by Tricyclohexylphosphine cyclopalladated ferrocenylimine complexes
Transition Metal Chemistry, 2009Co-Authors: Junfang Gong, Maoping SongAbstract:Tricyclohexylphosphine-cyclopalladated ferrocenylimine complexes were found to be very efficient catalysts for the one-pot borylation/Suzuki cross-coupling reactions of aryl chlorides with bis(pinacolato)diboron. Typically, using 0.5–1.0 mol% of catalyst in the presence of 3.0 equivalents of K2CO3 as base in dioxane at 100 °C provided the corresponding symmetrical biaryls in good to excellent yields.
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Tricyclohexylphosphine cyclopalladated ferrocenylimine complexes synthesis crystal structures and application in suzuki and heck reactions
Dalton Transactions, 2006Co-Authors: Junfang Gong, Sufang Yue, Yu ZhuAbstract:A series of novel Tricyclohexylphosphine (PCy3)-cyclopalladated ferrocenylimine complexes 2c–2g have been easily synthesized. These new palladacycles are thermally stable and are not sensitive to air and moisture. Their detailed structures have been determined by single-crystal X-ray analysis and six different types of intermolecular hydrogen bonds are found to be existed in the crystals of these complexes. The use of 2c–2g as catalysts for Suzuki and Heck reactions was examined. They were found to be very efficient for the Suzuki reaction of aryl chlorides with phenylboronic acid. Typically, using 0.1 mol% of catalyst in the presence of 1.5 equivalent of Cs2CO3 as base in dioxane at 100 °C provided coupled products in excellent yields. These complexes also displayed good activity in the Heck reaction of a range of aryl bromides with acrylic acid ethyl ester although they were not particularly useful for the activation of aryl chlorides.
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efficient suzuki coupling of aryl chlorides catalyzed by Tricyclohexylphosphine adducts of cyclopalladated ferrocenylimines
Journal of Organometallic Chemistry, 2005Co-Authors: Junfang Gong, Guangyu Liu, Yu ZhuAbstract:Abstract The air and moisture stable Tricyclohexylphosphine (PCy3) adducts of dimeric cyclopalladated ferrocenylimines 5 and 6 have been easily synthesized and successfully used in palladium-catalyzed Suzuki cross-coupling of aryl chlorides. Using 0.1 mol% of 6 in the presence of 2 equivalent of Cs2CO3 as base in dioxane at 100 °C provided coupled products in excellent yields in the reaction of non-activated and deactivated aryl chlorides with phenylboronic acid. For activated chlorides such as 4-chloronitrobenzene and 4-chloroacetophenone, the catalyst loadings could be lowered to 0.01 mol% without loss of activity.
