The Experts below are selected from a list of 5988 Experts worldwide ranked by ideXlab platform
Geoffrey A Ozin - One of the best experts on this subject based on the ideXlab platform.
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aluminum 2p silane complex and photoreversible oxidative addition Reductive Elimination Reaction al 2p sih4 tautm sih3alh 1 al 2p sih4 complex
The Journal of Physical Chemistry, 1991Co-Authors: Michael A Lefcourt, Geoffrey A OzinAbstract:Matrix-isolation investigations were carried out on samples consisting of individual aluminum atoms dispersed throughout silane (SiH{sub 4})-containing matrices and other related substrate materials at 12 K. UV-vis and EPR spectroscopies helped in the determination of a ground-state complex between {sup 2}P Al atoms and SiH{sub 4} molecules appearing upon matrix formation. The substitution of SiD{sub 4} for SiH{sub 4} caused narrowing of the absorptions associated with aluminum in both the experimental techniques employed, giving further support for the existence of ground-state complex. Further characterization of the complex was aided by results obtained from EPR spectral simulations and a series of ab initio self-consistent-field geometry optimization calculations. The EPR spectral simulations allowed g values, hyperfine splittings, and atomic orbital spin densities to be reported for the complex along with the ab initio results which supported the choice of a three-center, two-electron Al({eta}{sup 2}-SiH{sub 4}) side-on 'agostic' interaction scheme as the most probable bonding picture for the aluminum/silane ground-state complex.
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al sup 2 p l brace sih sub 4 r brace complex and photoreversible oxidative addition Reductive Elimination Reaction al sup 2 p l brace sih sub 4 r brace leftrightarrow sih sub 3 alh 2 al sup 2 p l brace sih sub 4 r brace leftrightarrow sih sub 3 alh Reaction
The Journal of Physical Chemistry, 1991Co-Authors: Michael A Lefcourt, Geoffrey A OzinAbstract:Brief 400-nm photolysis of 1:10 silane/argon matrices containing monatomically isolated aluminum results in the formation of the insertion product silylaluminum hydride (SiH{sub 3}AlH), most likely via an oxidative addition mechanism. The techniques of UV-vis, EPR, and infrared spectroscopy enabled the identification and characterization of this molecule. The photolytic generation of this species paralleled the formation of methylaluminum hydride (CH{sub 3}AlH) studied previously in the authors laboratory. EPR spectral simulations and ab initio self-consistent-field molecular orbital (SCF MO) calculations were employed to help in the characterization of silylaluminum hydride. The EPR spectral parameters extracted from the raw data via the computer simulations, along with subsequently calculated atomic orbital spin densities, determined that the molecule was a bent, orthorhombic species. The SCF MO calculated bond angle at the Al atom was shown to be 118.80{degree}. Secondary photolysis of the aluminum/silane matrix sample resulted in the conversion of the insertion product back to that of the ground-state complex most likely by a Reductive Elimination mechanism.
Michael A Lefcourt - One of the best experts on this subject based on the ideXlab platform.
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aluminum 2p silane complex and photoreversible oxidative addition Reductive Elimination Reaction al 2p sih4 tautm sih3alh 1 al 2p sih4 complex
The Journal of Physical Chemistry, 1991Co-Authors: Michael A Lefcourt, Geoffrey A OzinAbstract:Matrix-isolation investigations were carried out on samples consisting of individual aluminum atoms dispersed throughout silane (SiH{sub 4})-containing matrices and other related substrate materials at 12 K. UV-vis and EPR spectroscopies helped in the determination of a ground-state complex between {sup 2}P Al atoms and SiH{sub 4} molecules appearing upon matrix formation. The substitution of SiD{sub 4} for SiH{sub 4} caused narrowing of the absorptions associated with aluminum in both the experimental techniques employed, giving further support for the existence of ground-state complex. Further characterization of the complex was aided by results obtained from EPR spectral simulations and a series of ab initio self-consistent-field geometry optimization calculations. The EPR spectral simulations allowed g values, hyperfine splittings, and atomic orbital spin densities to be reported for the complex along with the ab initio results which supported the choice of a three-center, two-electron Al({eta}{sup 2}-SiH{sub 4}) side-on 'agostic' interaction scheme as the most probable bonding picture for the aluminum/silane ground-state complex.
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al sup 2 p l brace sih sub 4 r brace complex and photoreversible oxidative addition Reductive Elimination Reaction al sup 2 p l brace sih sub 4 r brace leftrightarrow sih sub 3 alh 2 al sup 2 p l brace sih sub 4 r brace leftrightarrow sih sub 3 alh Reaction
The Journal of Physical Chemistry, 1991Co-Authors: Michael A Lefcourt, Geoffrey A OzinAbstract:Brief 400-nm photolysis of 1:10 silane/argon matrices containing monatomically isolated aluminum results in the formation of the insertion product silylaluminum hydride (SiH{sub 3}AlH), most likely via an oxidative addition mechanism. The techniques of UV-vis, EPR, and infrared spectroscopy enabled the identification and characterization of this molecule. The photolytic generation of this species paralleled the formation of methylaluminum hydride (CH{sub 3}AlH) studied previously in the authors laboratory. EPR spectral simulations and ab initio self-consistent-field molecular orbital (SCF MO) calculations were employed to help in the characterization of silylaluminum hydride. The EPR spectral parameters extracted from the raw data via the computer simulations, along with subsequently calculated atomic orbital spin densities, determined that the molecule was a bent, orthorhombic species. The SCF MO calculated bond angle at the Al atom was shown to be 118.80{degree}. Secondary photolysis of the aluminum/silane matrix sample resulted in the conversion of the insertion product back to that of the ground-state complex most likely by a Reductive Elimination mechanism.
Teresa Headgordon - One of the best experts on this subject based on the ideXlab platform.
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interplay of water and a supramolecular capsule for catalysis of Reductive Elimination Reaction from gold
Nature Communications, 2020Co-Authors: Valerie Vaissier Welborn, Teresa HeadgordonAbstract:Supramolecular assemblies have gained tremendous attention due to their ability to catalyze Reactions with the efficiencies of natural enzymes. Using ab initio molecular dynamics, we identify the origin of the catalysis by the supramolecular capsule Ga4L612- on the Reductive Elimination Reaction from gold complexes and assess their similarity to natural enzymes. By comparing the free energies of the reactants and transition states for the catalyzed and uncatalyzed Reactions, we determine that an encapsulated water molecule generates electric fields that contributes the most to the reduction in the activation free energy. Although this is unlike the biomimetic scenario of catalysis through direct host-guest interactions, the electric fields from the nanocage also supports the transition state to complete the Reductive Elimination Reaction with greater catalytic efficiency. However it is also shown that the nanocage poorly organizes the interfacial water, which in turn creates electric fields that misalign with the breaking bonds of the substrate, thus identifying new opportunities for catalytic design improvements in nanocage assemblies.
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interplay of water and a supramolecular capsule for catalysis of Reductive Elimination Reaction from gold
arXiv: Chemical Physics, 2019Co-Authors: Valerie Vaissier Welborn, Teresa HeadgordonAbstract:Supramolecular assemblies have gained tremendous attention due to their apparent ability to catalyze Reactions with the efficiencies of natural enzymes. Using Born-Oppenheimer molecular dynamics and density functional theory, we identify the origin of the catalytic power of the supramolecular assembly Ga$_4$L$_{612-}$ on the Reductive Elimination Reaction from gold complexes and their similarity to enzymes. By comparing the catalyzed and uncatalyzed Reaction in explicit solvent to identify the Reaction free energies of the reactants, transition states, and products, we determine that a catalytic moiety -- an encapsulated water molecule -- generates electric fields that contribute significant reduction in the activation free energy. Although this is unlike the biomimetic scenario of catalysis through direct host-guest interactions, the nanocage host preconditions the transition state for greater sensitivity to electric field projections onto the breaking carbon bonds to complete the Reductive Elimination Reaction with greater catalytic efficiency. However it is also shown that the nanocage poorly organizes the interfacial water, which in turn creates electric fields that misalign with the breaking bonds of the substrate, thus identifying new opportunities for catalytic design improvements in nanocage assemblies.
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an encapsulated water governs catalysis in a supramolecular capsule for Reductive Elimination Reaction from gold
2019Co-Authors: Valerie Vaissier Welborn, Teresa HeadgordonAbstract:Supramolecular assemblies have gained tremendous attention due to their apparent ability to catalyze Reactions with the efficiencies of natural enzymes. Using Born-Oppenheimer molecular dynamics and density functional theory, we identify the origin of the catalytic power of the supramolecular assembly Ga$_4$L$_{612-}$ on the Reductive Elimination Reaction from gold complexes and their similarity to enzymes. By comparing the catalyzed and uncatalyzed Reaction in explicit solvent to identify the Reaction free energies of the reactants, transition states, and products, we determine that a catalytic moiety -- an encapsulated water molecule -- generates electric fields that contribute significant reduction in the activation free energy. Although this is unlike the biomimetic scenario of catalysis through direct host-guest interactions, the nanocage host preconditions the transition state for greater sensitivity to electric field projections onto the breaking carbon bonds to complete the Reductive Elimination Reaction with greater catalytic efficiency. However it is also shown that the nanocage poorly organizes the interfacial water, which in turn creates electric fields that misalign with the breaking bonds of the substrate, thus identifying new opportunities for catalytic design improvements in nanocage assemblies.
Anvarhusein A Isab - One of the best experts on this subject based on the ideXlab platform.
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nmr and kinetic studies of the interactions of au cis dach cl2 cl and au cis dach 2 cl3 with potassium cyanide in aqueous solution
Journal of Coordination Chemistry, 2014Co-Authors: Adam A A Seliman, Muhammad Altaf, Abdelnasser Kawde, Mohammed I M Wazeer, Anvarhusein A IsabAbstract:The interactions of [Au(cis-DACH)Cl2]Cl and [Au(cis-DACH)2]Cl3 [where cis-DACH is cis-1,2-diaminocyclohexane] with enriched KCN were carried out in CD3OD and D2O, respectively. The Reaction pathways of these complexes were studied by 1H, 13C, 15N NMR, UV spectrophotometry, and electrochemistry. The kinetic data for the Reaction of cyanide with [Au(cis-DACH)2]Cl3 are k = 18 M−1s−1, ∆H≠ = 11 kJ M−1, ∆S≠ = −185 JK−1 M−1, and Ea = 13 kJ M−1 with square wave voltammetric (SWV) peak +1.35 V, whereas the kinetic data for the Reaction of cyanide ion with [Au(cis-DACH)Cl2]Cl are k = 148 M−1s−1, ∆H≠ = 39 kJM−1, ∆S≠ = −80 JK-1 M−1, and Ea = 42 kJM−1 along with SWV peak +0.82 V, indicating much higher reactivity of [Au(cis-DACH)Cl2]Cl toward cyanide than [Au(cis-DACH)2]Cl3. The interaction of these complexes with potassium cyanide resulted in an unstable [Au(13CN)4]− species which readily underwent Reductive Elimination Reaction to generate [Au(13CN)2]− and cyanogen.
Valerie Vaissier Welborn - One of the best experts on this subject based on the ideXlab platform.
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interplay of water and a supramolecular capsule for catalysis of Reductive Elimination Reaction from gold
Nature Communications, 2020Co-Authors: Valerie Vaissier Welborn, Teresa HeadgordonAbstract:Supramolecular assemblies have gained tremendous attention due to their ability to catalyze Reactions with the efficiencies of natural enzymes. Using ab initio molecular dynamics, we identify the origin of the catalysis by the supramolecular capsule Ga4L612- on the Reductive Elimination Reaction from gold complexes and assess their similarity to natural enzymes. By comparing the free energies of the reactants and transition states for the catalyzed and uncatalyzed Reactions, we determine that an encapsulated water molecule generates electric fields that contributes the most to the reduction in the activation free energy. Although this is unlike the biomimetic scenario of catalysis through direct host-guest interactions, the electric fields from the nanocage also supports the transition state to complete the Reductive Elimination Reaction with greater catalytic efficiency. However it is also shown that the nanocage poorly organizes the interfacial water, which in turn creates electric fields that misalign with the breaking bonds of the substrate, thus identifying new opportunities for catalytic design improvements in nanocage assemblies.
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interplay of water and a supramolecular capsule for catalysis of Reductive Elimination Reaction from gold
arXiv: Chemical Physics, 2019Co-Authors: Valerie Vaissier Welborn, Teresa HeadgordonAbstract:Supramolecular assemblies have gained tremendous attention due to their apparent ability to catalyze Reactions with the efficiencies of natural enzymes. Using Born-Oppenheimer molecular dynamics and density functional theory, we identify the origin of the catalytic power of the supramolecular assembly Ga$_4$L$_{612-}$ on the Reductive Elimination Reaction from gold complexes and their similarity to enzymes. By comparing the catalyzed and uncatalyzed Reaction in explicit solvent to identify the Reaction free energies of the reactants, transition states, and products, we determine that a catalytic moiety -- an encapsulated water molecule -- generates electric fields that contribute significant reduction in the activation free energy. Although this is unlike the biomimetic scenario of catalysis through direct host-guest interactions, the nanocage host preconditions the transition state for greater sensitivity to electric field projections onto the breaking carbon bonds to complete the Reductive Elimination Reaction with greater catalytic efficiency. However it is also shown that the nanocage poorly organizes the interfacial water, which in turn creates electric fields that misalign with the breaking bonds of the substrate, thus identifying new opportunities for catalytic design improvements in nanocage assemblies.
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an encapsulated water governs catalysis in a supramolecular capsule for Reductive Elimination Reaction from gold
2019Co-Authors: Valerie Vaissier Welborn, Teresa HeadgordonAbstract:Supramolecular assemblies have gained tremendous attention due to their apparent ability to catalyze Reactions with the efficiencies of natural enzymes. Using Born-Oppenheimer molecular dynamics and density functional theory, we identify the origin of the catalytic power of the supramolecular assembly Ga$_4$L$_{612-}$ on the Reductive Elimination Reaction from gold complexes and their similarity to enzymes. By comparing the catalyzed and uncatalyzed Reaction in explicit solvent to identify the Reaction free energies of the reactants, transition states, and products, we determine that a catalytic moiety -- an encapsulated water molecule -- generates electric fields that contribute significant reduction in the activation free energy. Although this is unlike the biomimetic scenario of catalysis through direct host-guest interactions, the nanocage host preconditions the transition state for greater sensitivity to electric field projections onto the breaking carbon bonds to complete the Reductive Elimination Reaction with greater catalytic efficiency. However it is also shown that the nanocage poorly organizes the interfacial water, which in turn creates electric fields that misalign with the breaking bonds of the substrate, thus identifying new opportunities for catalytic design improvements in nanocage assemblies.