1
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Ariai J, Gellrich U. The entropic penalty for associative reactions and their physical treatment during routine computations. Phys Chem Chem Phys 2023; 25:14005-14015. [PMID: 37161492 DOI: 10.1039/d3cp00970j] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
A systematic study of the entropic penalty for associative reactions is presented. It is shown that computed solution-phase Gibbs free energies typically overestimate entropic contributions. This entropic penalty for associative reactions in solution, i.e., if the number of particles decreases along the reaction coordinate (sum of stoichiometric numbers ), originates from the insufficient treatment of entropic effects by implicit solvent models. We propose an additive correction scheme to Gibbs free energies that is suitable for routine applications by non-expert users. This correction is based on Garza's formalism for the solution-phase entropy [A. J. Garza, J. Chem. Theory Comput., 2019, 15, 3204.] that is physically sound and embedded into an efficient black-box type algorithm. To critically evaluate the entropic penalty and its proposed treatment, we compiled an experimental benchmark set of 31 ΔrG and 22 in 15 different solvents. Using a representative best-practice computational protocol (at wave function theory (WFT) based DLPNO-CCSD(T) and density functional theory (DFT) based revDSD-PBEP86-D4 level with an implicit solvent model), we determined a sizeable entropic penalty ranging from 2-11 kcal mol-1. Using the correction scheme presented herein, the entropic penalty is corrected to the chemical accuracy of ≤1 kcal mol-1 (WFT and DFT). The same applies to at the WFT level. Barriers at the DFT level are overestimated by 2 kcal mol-1 (classic) and underestimated by 2 kcal mol-1 (corrected). This effect is attributed to the finding that barriers computed at the DFT level are systematically 2-3 kcal mol-1 lower than barriers obtained with WFT.
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Affiliation(s)
- Jama Ariai
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.
| | - Urs Gellrich
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.
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2
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Conquest OJ, Roman T, Marianov A, Kochubei A, Jiang Y, Stampfl C. Calculating Entropies of Large Molecules in Aqueous Phase. J Chem Theory Comput 2021; 17:7753-7771. [PMID: 34860016 DOI: 10.1021/acs.jctc.1c00848] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Entropy benchmarking of different sized molecules in aqueous phase is carried out for known solvation models, where we compare geometry and solvation cavity packing parameters, which allows us to improve the accuracy of the obtained entropy values using empirical corrections. A comparison of solvation entropy models is conducted for a benchmarking set of 56 molecules, showing how an accurate description of cavitation entropy and its hindrance on other entropy values is important for large-sized solute molecules. Finally, we compare reaction free energies with entropies calculated using the most accurate solvation model considered, where we demonstrate a significant improvement in the accuracy relative to experimental values.
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Affiliation(s)
- Oliver J Conquest
- School of Physics, The University of Sydney, Sydney, NSW 2006, Australia.,The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia
| | - Tanglaw Roman
- School of Physics, The University of Sydney, Sydney, NSW 2006, Australia.,The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia.,Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia.,Flinders Institute for Nanoscale Science and Technology, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Aleksei Marianov
- School of Engineering, Macquarie University, Sydney, NSW 2109, Australia
| | - Alena Kochubei
- School of Engineering, Macquarie University, Sydney, NSW 2109, Australia
| | - Yijao Jiang
- School of Engineering, Macquarie University, Sydney, NSW 2109, Australia
| | - Catherine Stampfl
- School of Physics, The University of Sydney, Sydney, NSW 2006, Australia.,The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia
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3
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Abstract
The entropies of molecules in solution are often calculated using gas phase formulas. It is assumed that, because implicit solvation models are fitted to reproduce free energies, this is sufficient for modeling reactions in solution. However, this procedure exaggerates entropic effects in processes that change molecularity. Here, computationally efficient (i.e., having similar cost as gas phase entropy calculations) approximations for determining solvation entropy are proposed to address this issue. The Sω, Sϵ, and S ϵα models are nonempirical and rely only on physical arguments and elementary properties of the medium (e.g., density and relative permittivity). For all three methods, average errors as compared to experiment are within chemical accuracy for 110 solvation entropies, 11 activation entropies in solution, and 32 vaporization enthalpies. The models also make predictions regarding microscopic and bulk properties of liquids which prove to be accurate. These results imply that Δ Hsol and Δ Ssol can be described separately and with less reliance on parametrization by a combination of the methods presented here with existing, reparametrized, implicit solvation models.
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Affiliation(s)
- Alejandro J Garza
- The Dow Chemical Company , 1776 Building , Midland , Michigan 48674 , United States
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4
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Garza AJ, Pakhira S, Bell AT, Mendoza-Cortes JL, Head-Gordon M. Reaction mechanism of the selective reduction of CO 2 to CO by a tetraaza [Co IIN 4H] 2+ complex in the presence of protons. Phys Chem Chem Phys 2018; 20:24058-24064. [PMID: 30204173 DOI: 10.1039/c8cp01963k] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The tetraaza [CoIIN4H]2+ complex (1) is remarkable for its ability to selectively reduce CO2 to CO with 45% Faradaic efficiency and a CO to H2 ratio of 3 : 2. We employ density functional theory (DFT) to determine the reasons behind the unusual catalytic properties of 1 and the most likely mechanism for CO2 reduction. The selectivity for CO2 over proton reduction is explained by analyzing the catalyst's affinity for the possible ligands present under typical reaction conditions: acetonitrile, water, CO2, and bicarbonate. After reduction of the catalyst by two electrons, formation of [CoIN4H]+-CO2- is strongly favored. Based on thermodynamic and kinetic data, we establish that the only likely route for producing CO from here consists of a protonation step to yield [CoIN4H]+-CO2H, followed by reaction with CO2 to form [CoIIN4H]2+-CO and bicarbonate. This conclusion corroborates the idea of a direct role of CO2 as a Lewis acid to assist in C-O bond dissociation, a conjecture put forward by other authors to explain recent experimental observations. The pathway to formic acid is predicted to be forbidden by high activation barriers, in accordance with the products that are known to be generated by 1. Calculated physical observables such as standard reduction potentials and the turnover frequency for our proposed catalytic cycle are in agreement with available experimental data reported in the literature. The mechanism also makes a prediction that may be experimentally verified: that the rate of CO formation should increase linearly with the partial pressure of CO2.
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Affiliation(s)
- Alejandro J Garza
- Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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5
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Garza AJ, Bell AT, Head-Gordon M. Is Subsurface Oxygen Necessary for the Electrochemical Reduction of CO 2 on Copper? J Phys Chem Lett 2018; 9:601-606. [PMID: 29341623 DOI: 10.1021/acs.jpclett.7b03180] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
It has recently been proposed that subsurface oxygen is crucial for the adsorption and subsequent electroreduction of CO2 on copper. Using density functional theory, we have studied the stability and diffusion of subsurface oxygen in single crystals of copper exposing (111) and (100) facets. Oxygen is at least 1.5 eV more stable on the surface than beneath it for both crystal orientations; interstitial sites are too small to accommodate oxygen. The rate of atomic oxygen diffusion from one layer below a Cu(111) surface to the surface is 5 × 103 s-1. Oxygen can survive longer in deeper layers, but it does not promote CO2 adsorption there. Diffusion of subsurface oxygen is easier to the less-dense Cu(100) surface, even from lower layers (rate ≈ 1 × 107 s-1). Once the applied voltage and dispersion forces are properly modeled, we find that subsurface oxygen is unnecessary for CO2 adsorption on copper.
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Affiliation(s)
- Alejandro J Garza
- Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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6
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Garza AJ, Bell AT, Head-Gordon M. Mechanism of CO2 Reduction at Copper Surfaces: Pathways to C2 Products. ACS Catal 2018. [DOI: 10.1021/acscatal.7b03477] [Citation(s) in RCA: 405] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alejandro J. Garza
- Joint
Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alexis T. Bell
- Department
of Chemical and Biomolecular Engineering, University of California at Berkeley, Berkeley, California 94720, United States
| | - Martin Head-Gordon
- Department
of Chemistry, University of California at Berkeley, Berkeley, California 94720, United States
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7
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Legnani L, Toma L, Caramella P, Chiacchio MA, Giofrè S, Delso I, Tejero T, Merino P. Computational Mechanistic Study of Thionation of Carbonyl Compounds with Lawesson’s Reagent. J Org Chem 2016; 81:7733-40. [DOI: 10.1021/acs.joc.6b01420] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- L. Legnani
- Dipartimento
di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - L. Toma
- Dipartimento
di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - P. Caramella
- Dipartimento
di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - M. A. Chiacchio
- Dipartimento
di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
- Dipartimento
di Scienze del Farmaco, Università di Catania, V. le A.
Doria 6, 95125 Catania, Italy
| | - S. Giofrè
- Dipartimento
di Scienze chimiche, biologiche, farmaceutiche e ambientali, Università di Messina, Via Stagno d’Alcontres, 98166 Messina, Italy
| | - I. Delso
- Laboratorio
de Síntesis Asimétrica, Instituto de Síntesis
Quimica y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
| | - T. Tejero
- Laboratorio
de Síntesis Asimétrica, Instituto de Síntesis
Quimica y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
| | - P. Merino
- Laboratorio
de Síntesis Asimétrica, Instituto de Síntesis
Quimica y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
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8
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Zhang G, Zhang W, Luan Y, Han X, Ding C. PEG Click-Triazole Palladacycle: An Efficient Precatalyst for Palladium-Catalyzed Suzuki-Miyaura and Copper-free Sonogashira Reactions in Neat Water. CHINESE J CHEM 2015. [DOI: 10.1002/cjoc.201500167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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9
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Maxwell CI, Mosey NJ, Stan Brown R. DFT Computational Study of the Methanolytic Cleavage of DNA and RNA Phosphodiester Models Promoted by the Dinuclear Zn(II) Complex of 1,3-Bis(1,5,9-triazacyclododec-1-yl)propane. J Am Chem Soc 2013; 135:17209-22. [DOI: 10.1021/ja4088264] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
| | - Nicholas J. Mosey
- Department
of Chemistry, Queen’s University, Kingston, Ontario, Canada K7L 3N6
| | - R. Stan Brown
- Department
of Chemistry, Queen’s University, Kingston, Ontario, Canada K7L 3N6
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10
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LIANG JINXIA, WANG BINJU, CAO ZEXING. THE MECHANISM OF ACID-CATALYZED DECARBOXYLATION OF PYRROLE-2-CARBOXYLIC ACID: INSIGHTS FROM CLUSTER-CONTINUUM MODEL CALCULATIONS. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2013. [DOI: 10.1142/s021963361350017x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The decarboxylation of pyrrole-2-carboxylic acid comprises the addition of water to the carboxyl group and the C–C bond cleavage leading to the protonated carbonic acid. Herein possible concerted and stepwise mechanisms for the C-protonated and O-protonated pathways were extensively investigated by using the cluster-continuum model. The calculated results indicate that the initial hydration or the nucleophilic attack of water at the carbonyl group of both C- and O-protonated derivatives is the rate-determining step for the overall reaction, and the O-protonated pathway will dominate the whole reaction. The predicted activation Gibbs energies for the overall reaction initialized by the O-protonated species fall in the range of 83.3 ∼ 123.0 kJ/mol, showing good agreement with experimental values of 91.6 ∼ 101.3 kJ/mol. On the basis of extensive calculations, the remarkable dependence of the predicted mechanisms and thermodynamic values on the number of explicit water molecules in the cluster-continuum model was discussed.
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Affiliation(s)
- JINXIA LIANG
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial, Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, P. R. China
| | - BINJU WANG
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial, Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, P. R. China
| | - ZEXING CAO
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial, Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, P. R. China
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11
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Wang B, Cao Z. How water molecules modulate the hydration of CO2in water solution: Insight from the cluster-continuum model calculations. J Comput Chem 2012; 34:372-8. [DOI: 10.1002/jcc.23144] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 09/03/2012] [Accepted: 09/12/2012] [Indexed: 11/10/2022]
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12
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Raycroft MAR, Maxwell CI, Oldham RAA, Andrea AS, Neverov AA, Brown RS. Trifunctional metal ion-catalyzed solvolysis: Cu(II)-promoted methanolysis of N,N-bis(2-picolyl) benzamides involves unusual Lewis acid activation of substrate, delivery of coordinated nucleophile, powerful assistance of the leaving group departure. Inorg Chem 2012; 51:10325-33. [PMID: 22971051 DOI: 10.1021/ic301454y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The methanolyses of Cu(II) complexes of a series of N,N-bis(2-picolyl) benzamides (4a-g) bearing substituents X on the aromatic ring were studied under (s)(s)pH-controlled conditions at 25 °C. The active form of the complexes at neutral (s)(s)pH has a stoichiometry of 4:Cu(II):((-)OCH(3))(HOCH(3)) and decomposes unimolecularly with a rate constant k(x). A Hammett plot of log(k(x)) vs σ(x) values has a ρ(x) of 0.80 ± 0.05. Solvent deuterium kinetic isotope effects of 1.12 and 1.20 were determined for decomposition of the 4-nitro and 4-methoxy derivatives, 4b:Cu(II):((-)OCH(3))(HOCH(3)) and 4g:Cu(II):((-)OCH(3))(HOCH(3)), in the plateau region of the (s)(s)pH/log(k(x)) profiles in both CH(3)OH and CH(3)OD. Activation parameters for decomposition of these complexes are ΔH(++) = 19.1 and 21.3 kcal mol(-1) respectively and ΔS(++) = -5.1 and -2 cal K(-1) mol(-1). Density functional theory (DFT) calculations for the reactions of the Cu(II):((-)OCH(3))(HOCH(3)) complexes of 4a,b and g (4a, X = 3,5-dinitro) were conducted to probe the relative transition state energies and geometries of the different states. The experimental and computational data support a mechanism where the metal ion is coordinated to the N,N-bis(2-picolyl) amide unit and positioned so that it permits delivery of a coordinated Cu(II):((-)OCH(3)) nucleophile to the C═O in the rate-limiting transition state (TS) of the reaction. This proceeds to a tetrahedral intermediate INT, occupying a shallow minimum on the free energy surface with the Cu(II) coordinated to both the methoxide and the amidic N. Breakdown of INT is a virtually barrierless process, involving a Cu(II)-assisted departure of the bis(2-picolyl)amide anion. The analysis of the data points to a trifunctional role for the metal ion in the solvolysis mechanism where it activates intramolecular nucleophilic attack on the C═O group by coordination to an amidic N in the first step of the reaction and subsequently assists leaving group departure in the second step. The catalysis is very large; compared with the second order rate constant for methoxide attack on 4b, the computed reaction of CH3O(-) and 4b:Cu(II):(HOCH(3))(2) is accelerated by roughly 2.0 × 10(16) times.
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Affiliation(s)
- Mark A R Raycroft
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6
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13
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Barrera IF, Maxwell CI, Neverov AA, Brown RS. Cu(II)-Promoted Methanolysis of N,N-Dipicolylacetamide. Multistep Activation by Decoupling of >N̈–C═O Resonance via Cu(II)–N Binding, Delivery of the Cu(II):(−OCH3) Nucleophile, and Metal Ion Assistance of the Departure of the Leaving Group. J Org Chem 2012; 77:4156-60. [DOI: 10.1021/jo300329x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Alexei A. Neverov
- Department of Chemistry, Queen’s University, Kingston, Ontario, Canada K7L 3N6
| | - R. Stan Brown
- Department of Chemistry, Queen’s University, Kingston, Ontario, Canada K7L 3N6
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14
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Development of metal-ion containing catalysts for the decomposition of phosphorothioate esters. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:433-42. [PMID: 22381961 DOI: 10.1016/j.bbapap.2012.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/08/2012] [Accepted: 02/11/2012] [Indexed: 11/23/2022]
Abstract
The widespread use of phosphorothioate esters as agricultural pesticides, chemical weapons and mechanistic probes in enzymology has sparked interest in the reactivity of these thio-substituted analogues of phosphate esters. In this brief account, we summarize the recent developments in our understanding of the mechanisms of hydrolysis (and solvolysis in methanol) of phosphorothioates containing a sulfur atom in the bridging and/or non-bridging position. A small number of highly efficient catalytic systems containing the metal ions La(III), Pd(II), Cu(II) and Zn(II) have been developed to promote the degradation of the various classes of phosphorothioate esters. The mechanisms of the base promoted solvolytic reactions in water and methanol and those of the metal catalyzed cleavage are presented, as well as a discussion of the energetics of the catalytic processes and other salient features. The aim of this review is to provide the reader with a contemporary physical organic description of phosphorothioate ester cleavage. This article is part of a Special Issue entitled: Chemistry and mechanism of phosphatases, diesterases and triesterases.
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15
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Liu CT, Maxwell CI, Pipe SG, Neverov AA, Mosey NJ, Brown RS. Methanolysis of Thioamide Promoted by a Simple Palladacycle Is Accelerated by 108 over the Methoxide-Catalyzed Reaction. J Am Chem Soc 2011; 133:20068-71. [DOI: 10.1021/ja209605r] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- C. Tony Liu
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6
| | - Christopher I. Maxwell
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6
| | - Stephanie G. Pipe
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6
| | - Alexei A. Neverov
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6
| | - Nicholas J. Mosey
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6
| | - R. Stan Brown
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6
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16
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Maxwell CI, Liu CT, Neverov AA, Mosey NJ, Brown RS. Transition from concerted to stepwise processes as a function of leaving group ability: density functional theory and experimental study of lyoxide-promoted cleavages of phosphorothioate and phosphate triesters in water and methanol. J PHYS ORG CHEM 2011. [DOI: 10.1002/poc.1938] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - C. Tony Liu
- Department of Chemistry; Queen's University; Kingston Ontario Canada K7L 3N6
| | - Alexei A. Neverov
- Department of Chemistry; Queen's University; Kingston Ontario Canada K7L 3N6
| | - Nicholas J. Mosey
- Department of Chemistry; Queen's University; Kingston Ontario Canada K7L 3N6
| | - Robert Stan Brown
- Department of Chemistry; Queen's University; Kingston Ontario Canada K7L 3N6
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17
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Wang B, Cao Z. Acid-catalyzed reactions of twisted amides in water solution: competition between hydration and hydrolysis. Chemistry 2011; 17:11919-29. [PMID: 21901771 DOI: 10.1002/chem.201101274] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/07/2011] [Indexed: 11/12/2022]
Abstract
The acid-catalyzed reactions of twisted amides in water solution were investigated by using cluster-continuum model calculations. In contrast to the previous widely suggested concerted hydration of the C=O group, our calculations show that the reaction proceeds in a practically stepwise manner, and that the hydration and hydrolysis channels of the C-N bond compete. The Eigen ion (H(3)O(+)) is the key species involved in the reaction, and it modulates the hydration and hydrolysis reaction pathways. The phenyl substitution in the twisted amide not only activates the N-CO bond, but also stabilizes the hydrolysis product through n(N)→π(phenyl) delocalization, leading exclusively to the hydrolysis product of the ring-opened carboxylic acid. Generally, the twisted amides are more active than the planar amides, and such a rate acceleration results mainly from the increase in exothermicity in the first N-protonation step; the second step of the nucleophilic attack is less affected by the twisting of the amide bond. The present results show good agreement with the available experimental observations.
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Affiliation(s)
- Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, PR China
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18
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Roiban GD, Serrano E, Soler T, Aullón G, Grosu I, Cativiela C, Martínez M, Urriolabeitia EP. Regioselective orthopalladation of (Z)-2-aryl-4-arylidene-5(4H)-oxazolones: scope, kinetico-mechanistic, and density functional theory studies of the C-H bond activation. Inorg Chem 2011; 50:8132-43. [PMID: 21806046 DOI: 10.1021/ic200564d] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Orthopalladated complexes derived from (Z)-2-aryl-4-arylidene-5(4H)-oxazolones have been prepared by reaction of the oxazolone with palladium acetate in acidic medium. The reaction is regioselective, only the ortho C-H bond of the arylidene ring being activated, producing a six-membered ring. The scope and reaction conditions of the orthopalladation are dependent on the acidity of the solvent. In CF(3)CO(2)H a large number of oxazolones can be metalated under mild conditions. As acidity decreases a lesser number of oxazolones can be efficiently palladated and harsher conditions must be used to achieve similar yields. The C-H bond activation in acidic medium agrees with an ambiphilic mechanism, as determined from kinetic measurements at variable temperature and pressure for different oxazolones substituted at the arylidene ring. The mechanism has been confirmed by density functional theory (DFT) calculations, where the formation of the six-membered ring is shown to be favored from both a kinetic and a thermodynamic perspective. In addition, the dependence of the reaction rate on the acidity of the medium has also been accounted for via a fine-tuning between the C-H agostic precoordination and the proton abstraction reaction in the overall process occurring on coordinatively saturated [Pd(κ(N)-oxazolone)(RCO(2)H)(3)](2+).
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Affiliation(s)
- Gheorghe-Doru Roiban
- Organic Chemistry Department, Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, 400028, Cluj-Napoca, Romania
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19
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Edwards DR, Maxwell CI, Harkness RW, Neverov AA, Mosey NJ, Stan Brown R. Experimental and computational determination of Brønsted coefficients for equilibrium transfer of the O
,O
-dimethyl phosphorothioyl group between oxyanion nucleophiles. J PHYS ORG CHEM 2011. [DOI: 10.1002/poc.1903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- David R. Edwards
- Department of Chemistry; Queen's University; Kingston Ontario K7L 3N6 Canada
| | | | - Robert W. Harkness
- Department of Chemistry; Queen's University; Kingston Ontario K7L 3N6 Canada
| | - Alexei A. Neverov
- Department of Chemistry; Queen's University; Kingston Ontario K7L 3N6 Canada
| | - Nicholas J. Mosey
- Department of Chemistry; Queen's University; Kingston Ontario K7L 3N6 Canada
| | - R. Stan Brown
- Department of Chemistry; Queen's University; Kingston Ontario K7L 3N6 Canada
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20
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Liu CT, Neverov AA, Brown RS. Palladacycle-Promoted Solvolytic Cleavage of O,O-Dimethyl O-Aryl Phosphorothioates. Converting a Phosphorane-Like Transition State to an Observable Intermediate. Inorg Chem 2011; 50:7852-62. [DOI: 10.1021/ic201062h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- C. Tony Liu
- Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Alexei A. Neverov
- Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - R. Stan Brown
- Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
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21
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Edwards DR, Neverov AA, Brown RS. Study on the Transesterification of Methyl Aryl Phosphorothioates in Methanol Promoted by Cd(II), Mn(II), and a Synthetic Pd(II) Complex. Inorg Chem 2011; 50:1786-97. [DOI: 10.1021/ic102220m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David R. Edwards
- Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Alexei A. Neverov
- Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - R. Stan Brown
- Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
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