1
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Aysin RR, Galkin KI. Adaptive carbonyl umpolung involving a carbanionic carbene Breslow intermediate: an alternative mechanism for NHC-mediated organocatalysis. Org Biomol Chem 2023; 21:8702-8707. [PMID: 37867444 DOI: 10.1039/d3ob01195j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Herein, we propose a novel mechanistic model for NHC-mediated carbonyl umpolung which involves the formation of a carbanionic carbene Breslow intermediate (CCBI). We have demonstrated theoretically that this reactive intermediate can be formed by inserting an aldehyde into the C4-H position of an N-aryl-substituted imidazolium-derived NHC via the generation of an H-bonded ditopic carbanionic NHC (dcNHC). Our DFT study on benzoin condensation has revealed that the mechanism of polarity inversion proceeding through the CCBI may be more energetically favorable than the classical mechanism of umpolung that uses the C2 carbene position in NHC. The potential existence of the CCBI highlights the dynamic and adaptive nature of NHC-mediated organocatalysis, particularly in relation to carbonyl umpolung. This finding also sheds light on new pathways in organocatalytic transformations employing the ambident reactivity of NHC, which may be particularly attractive for reactions involving furanic aldehydes and sterically encumbered N-aryl-substituted carbenes.
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Affiliation(s)
- Rinat R Aysin
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova, 28, 119991 Moscow, Russia
| | - Konstantin I Galkin
- Bauman Moscow State Technical University, 2nd Baumanskaya ul., 5/1, 105005 Moscow, Russia.
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, ul. Leninsky Prospekt, 47, 119991, Moscow, Russia
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2
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Stoppelman JP, McDaniel JG. Physics-based, neural network force fields for reactive molecular dynamics: Investigation of carbene formation from [EMIM +][OAc -]. J Chem Phys 2021; 155:104112. [PMID: 34525833 DOI: 10.1063/5.0063187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Reactive molecular dynamics simulations enable a detailed understanding of solvent effects on chemical reaction mechanisms and reaction rates. While classical molecular dynamics using reactive force fields allows significantly longer simulation time scales and larger system sizes compared with ab initio molecular dynamics, constructing reactive force fields is a difficult and complex task. In this work, we describe a general approach following the empirical valence bond framework for constructing ab initio reactive force fields for condensed phase simulations by combining physics-based methods with neural networks (PB/NNs). The physics-based terms ensure the correct asymptotic behavior of electrostatic, polarization, and dispersion interactions and are compatible with existing solvent force fields. NNs are utilized for a versatile description of short-range orbital interactions within the transition state region and accurate rendering of vibrational motion of the reacting complex. We demonstrate our methodology for a simple deprotonation reaction of the 1-ethyl-3-methylimidazolium cation with acetate to form 1-ethyl-3-methylimidazol-2-ylidene and acetic acid. Our PB/NN force field exhibits ∼1 kJ mol-1 mean absolute error accuracy within the transition state region for the gas-phase complex. To characterize the solvent modulation of the reaction profile, we compute potentials of mean force for the gas-phase reaction as well as the reaction within a four-ion cluster and benchmark against ab initio molecular dynamics simulations. We find that the surrounding ionic environment significantly destabilizes the formation of the carbene product, and we show that this effect is accurately captured by the reactive force field. By construction, the PB/NN potential may be directly employed for simulations of other solvents/chemical environments without additional parameterization.
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Affiliation(s)
- John P Stoppelman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
| | - Jesse G McDaniel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
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3
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Wild M, Stolz F, Naumov S, Abel B. On the in situ formation of carbenes in ionic liquids. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1974589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Martin Wild
- Leibniz Institute of Surface Engineering (IOM), Leipzig, Germany
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University Leipzig, Leipzig, Germany
| | - Ferdinand Stolz
- Leibniz Institute of Surface Engineering (IOM), Leipzig, Germany
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University Leipzig, Leipzig, Germany
| | - Sergej Naumov
- Leibniz Institute of Surface Engineering (IOM), Leipzig, Germany
| | - Bernd Abel
- Leibniz Institute of Surface Engineering (IOM), Leipzig, Germany
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University Leipzig, Leipzig, Germany
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4
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Galkin KI, Karlinskii BY, Kostyukovich AY, Gordeev EG, Ananikov VP. Ambident Reactivity of Imidazolium Cations as Evidence of the Dynamic Nature of N-Heterocyclic Carbene-Mediated Organocatalysis. Chemistry 2020; 26:8567-8571. [PMID: 32227612 DOI: 10.1002/chem.201905704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/27/2020] [Indexed: 11/10/2022]
Abstract
This work reveals ambident nucleophilic reactivity of imidazolium cations towards carbonyl compounds at the C2 or C4 carbene centers depending on the steric properties of the substrates and reaction conditions. Such an adaptive behavior indicates the dynamic nature of organocatalysis proceeding via a covalent interaction of imidazolium carbenes with carbonyl substrates and can be explained by generation of the H-bonded ditopic carbanionic carbenes.
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Affiliation(s)
- Konstantin I Galkin
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991, Moscow, Russia
| | - Bogdan Ya Karlinskii
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991, Moscow, Russia
| | - Alexander Yu Kostyukovich
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991, Moscow, Russia
| | - Evgeniy G Gordeev
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991, Moscow, Russia
| | - Valentine P Ananikov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991, Moscow, Russia
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5
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Blasius J, Elfgen R, Hollóczki O, Kirchner B. Glucose in dry and moist ionic liquid: vibrational circular dichroism, IR, and possible mechanisms. Phys Chem Chem Phys 2020; 22:10726-10737. [PMID: 32150178 DOI: 10.1039/c9cp06798a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquids and their mixtures with water show remarkable features in cellulose processing. For this reason, understanding the behavior of carbohydrates in ionic liquids is important. In the present study, we investigated three d-glucose isomers (α, β and open-chain) in 1-ethyl-3-methylimidazolium acetate in the presence and absence of water, through ab initio molecular dynamics simulations. In the complex hydrogen bonding network of these mixtures, the most interesting observation is that upon water addition every hydrogen bond elongates, except the glucose-glucose hydrogen bond for the open-chain and the α-form which shortens, clearly showing the beginning of the crystallization process. The ring glucose rearranges from on-top to in-plane and the open form changes from a coiled to a more linear arrangement when adding water which explains the contradiction that the center of mass distances of the glucose molecules with other glucose molecules grow while the hydrogen bonds shorten. The appearance of coiled open forms indicates that the previously suggested isomerization between these forms is possible and might play a role in the solubility of the related carbohydrates. The calculated IR and VCD spectra reveal insight into the intermolecular interactions, with good to excellent agreements with experimental spectra. Investigating the role of the cation, distances between the acidic carbon atom of the cation and the glucose carbon atom where ring closure and opening occurs are found, which are way shorter than dispersion-like interactions between aliphatic hydrocarbons.
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Affiliation(s)
- Jan Blasius
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4 + 6, D-53115 Bonn, Germany.
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6
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Brehm M, Thomas M, Gehrke S, Kirchner B. TRAVIS—A free analyzer for trajectories from molecular simulation. J Chem Phys 2020; 152:164105. [DOI: 10.1063/5.0005078] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- M. Brehm
- Institut für Chemie, Martin-Luther-Universität Halle–Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
| | - M. Thomas
- Institut für Chemie, Martin-Luther-Universität Halle–Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
| | - S. Gehrke
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - B. Kirchner
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
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7
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Hollóczki O. The Mechanism of N-Heterocyclic Carbene Organocatalysis through a Magnifying Glass. Chemistry 2020; 26:4885-4894. [PMID: 31797448 PMCID: PMC7187225 DOI: 10.1002/chem.201903021] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Indexed: 11/11/2022]
Abstract
The term "N-Heterocyclic carbene organocatalysis" is often invoked in organic synthesis for reactions that are catalyzed by different azolium salts in the presence of bases. Although the mechanism of these reactions is considered today evident, a closer look into the details that have been collected throughout the last century reveals that there are many open questions and even contradictions in the field. Emerging new theoretical and experimental results offer solutions to these problems, because they show that through considering alternative reaction mechanisms a more consistent picture on the catalytic process can be obtained. These novel perspectives will be able to extend the scope of the reactions that we call today N-heterocyclic carbene organocatalysis.
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Affiliation(s)
- Oldamur Hollóczki
- Mulliken Center for Theoretical ChemistryUniversity of BonnBeringstrasse 4+653115BonnGermany
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8
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Jain P, Chaudhari VR, Kumar A. Water-assisted stability of carbene: cyclic voltammetric investigation of 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid. Phys Chem Chem Phys 2019; 21:24126-24131. [PMID: 31657400 DOI: 10.1039/c9cp05033g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In this work, we report electrochemical studies on imidazolium-based ionic liquids with an objective to explore the possibility of carbene formation in their dilute aqueous solutions. Conventionally, water plays a detrimental role during investigations involving ionic liquids, and this role has been investigated via electrochemical studies in aqueous ionic liquid solutions. There are varying opinions regarding the influence of water on the physicochemical behaviour of ionic liquids that require an in-depth understanding. To eludicate the role of water, we attempted to evaluate the electrochemical performance of ionic liquids in water as a solvent, and the influence of water on ionic liquids was explored through feasibility and stability studies on carbene formed in an aqueous imidazolium-based ionic liquid solution. The electrochemical investigation of an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) revealed a redox couple. Detailed investigations suggest that reduction of the imidazolium cation occurs at the C2 position, with subsequent formation of carbene. Furthermore, an anodic peak was found to be associated with the oxidation of carbene. The coulometric process associated with the anodic peaks indicated that the two-electron oxidation of carbene occurred. The stability of carbene in water was evaluated through the use of different protic and aprotic solvents. The hydrogen bond-forming ability of carbene with water seems to be responsible for its improved stability in water.
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Affiliation(s)
- Preeti Jain
- Physical & Material Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.
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9
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Trinh TKH, Morlet-Savary F, Pinaud J, Lacroix-Desmazes P, Reibel C, Joyeux C, Le Nouen D, Métivier R, Brosseau A, Héroguez V, Chemtob A. Photoreduction of triplet thioxanthone derivative by azolium tetraphenylborate: a way to photogenerate N-heterocyclic carbenes. Phys Chem Chem Phys 2019; 21:17036-17046. [PMID: 31355381 DOI: 10.1039/c9cp03098k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although N-heterocyclic carbenes (NHCs) have brought profound changes in catalytic organic synthesis, their generation generally requires an inert atmosphere and harsh conditions. To overcome these limitations, an air-stable NHC photogenerator has been developed involving two mild components: 1,3-bis(mesityl)imidazolium tetraphenylborate (IMesH+BPh4-) and electronically excited isopropylthioxanthone (ITX). In this study, the photochemical mechanism is investigated via the accurate identification of the transient species and photoproducts. Electron transfer reaction between the excited triplet state of ITX and BPh4- is demonstrated as being the primary photochemical step. Nanosecond laser spectroscopy shows an efficient quenching and the formation of the expected ITX radical anion. The oxidized borane species is not observed, suggesting that this short-lived species could dissociate very rapidly to give the phenyl radical - successfully identified using electron paramagnetic resonance - and triphenylborane. As regards the final photoproducts, 1H and 13C NMR spectroscopies support the formation of the targeted NHC, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), suggesting the occurrence of a subsequent proton transfer reaction between ITX radical anion and imidazolium cation (IMesH+). Gas chromatography-mass spectrometry reveals three other products: biphenyl, isopropylthioxanthene and ITX. Their formation can be reconciled with a 2-step mechanism of photoinduced electron/proton transfer reactions. 11B NMR spectroscopy demonstrates that the main organoboron photoproduct is diphenylborinic acid formed by oxidation of BPh3. Due to its Lewis acidity, Ph2BOH can react with IMes to yield an NHC-boron adduct.
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Affiliation(s)
- Thi Kim Hoang Trinh
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRS, Université de Haute-Alsace, Mulhouse, France. and Université de Strasbourg, Strasbourg, France
| | - Fabrice Morlet-Savary
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRS, Université de Haute-Alsace, Mulhouse, France. and Université de Strasbourg, Strasbourg, France
| | - Julien Pinaud
- ICGM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | | | - Corine Reibel
- ICGM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Cécile Joyeux
- Laboratoire d'Innovation Moléculaire et Applications, LIMA, Université de Haute-Alsace, France
| | - Didier Le Nouen
- Laboratoire d'Innovation Moléculaire et Applications, LIMA, Université de Haute-Alsace, France
| | - Rémi Métivier
- Laboratoire PPSM, ENS Cachan, CNRS, Université Paris-Saclay, 94235, Cachan, France
| | - Arnaud Brosseau
- Laboratoire PPSM, ENS Cachan, CNRS, Université Paris-Saclay, 94235, Cachan, France
| | - Valérie Héroguez
- Université de Bordeaux, CNRS, Bordeaux INP, LCPO, UMR 5629, F-33600, Pessac, France
| | - Abraham Chemtob
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRS, Université de Haute-Alsace, Mulhouse, France. and Université de Strasbourg, Strasbourg, France
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10
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Trinh TKH, Malval J, Morlet‐Savary F, Pinaud J, Lacroix‐Desmazes P, Reibel C, Héroguez V, Chemtob A. Mixture of Azolium Tetraphenylborate with Isopropylthioxanthone: A New Class of N‐Heterocyclic Carbene (NHC) Photogenerator for Polyurethane, Polyester, and ROMP Polymers Synthesis. Chemistry 2019; 25:9242-9252. [DOI: 10.1002/chem.201901000] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/22/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Thi Kim Hoang Trinh
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRSUniversité de Haute-Alsace France
- Université de Strasbourg France
| | - Jean‐Pierre Malval
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRSUniversité de Haute-Alsace France
- Université de Strasbourg France
| | - Fabrice Morlet‐Savary
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRSUniversité de Haute-Alsace France
- Université de Strasbourg France
| | - Julien Pinaud
- Institut Charles Gerhardt Montpellier, ICGM UMR 5253Université de Montpellier, CNRS, ENSCM Montpellier France
| | - Patrick Lacroix‐Desmazes
- Institut Charles Gerhardt Montpellier, ICGM UMR 5253Université de Montpellier, CNRS, ENSCM Montpellier France
| | - Corine Reibel
- Institut Charles Gerhardt Montpellier, ICGM UMR 5253Université de Montpellier, CNRS, ENSCM Montpellier France
| | - Valérie Héroguez
- CNRSBordeaux INP, LCPO, UMR 5629Université de Bordeaux 33600 France
| | - Abraham Chemtob
- Institut de Science des Matériaux de Mulhouse, IS2M UMR 7361 CNRSUniversité de Haute-Alsace France
- Université de Strasbourg France
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11
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Brehm M, Pulst M, Kressler J, Sebastiani D. Triazolium-Based Ionic Liquids: A Novel Class of Cellulose Solvents. J Phys Chem B 2019; 123:3994-4003. [DOI: 10.1021/acs.jpcb.8b12082] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
| | - Martin Pulst
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
| | - Jörg Kressler
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
| | - Daniel Sebastiani
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
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12
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Brehm M, Sebastiani D. Simulating structure and dynamics in small droplets of 1-ethyl-3-methylimidazolium acetate. J Chem Phys 2018; 148:193802. [PMID: 30307180 DOI: 10.1063/1.5010342] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To investigate the structure and dynamics of small ionic liquid droplets in gas phase, we performed a DFT-based ab initio molecular dynamics study of several 1-ethyl-3-methylimidazolium acetate clusters in vacuum as well as a bulk phase simulation. We introduce an unbiased criterion for average droplet diameter and density. By extrapolation of the droplet densities, we predict the experimental bulk phase density with a deviation of only a few percent. The hydrogen bond geometry between cations and anions is very similar in droplets and bulk, but the hydrogen bond dynamics is significantly slower in the droplets, becoming slower with increasing system size, with hydrogen bond lifetimes up to 2000 ps. From a normal mode analysis of the trajectories, we identify the modes of the ring proton C-H stretching, which are strongly affected by hydrogen bonding. From analyzing these, we find that the hydrogen bond becomes weaker with increasing system size. The cations possess an increased concentration inside the clusters, whereas the anions show an excess concentration on the outside. Almost all anions point towards the droplet center with their carboxylic groups. Ring stacking is found to be a very important structural motif in the droplets (as in the bulk), but side chain interactions are only of minor importance. By using Voronoi tessellation, we define the exposed droplet surface and find that it consists mainly of hydrogen atoms from the cation's and anion's methyl and ethyl groups. Polar atoms are rarely found on the surface, such that the droplets appear completely hydrophobic on the outside.
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Affiliation(s)
- Martin Brehm
- Institut für Chemie-Theoretische Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Daniel Sebastiani
- Institut für Chemie-Theoretische Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
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13
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Donsbach C, Dehnen S. Formation of [(C
n
C
1
imTe)
4
Hg]
2+
(
n
= 6, 8) upon in‐situ Generation of Dialkylimidazole‐2‐Tellurones in Ionic Liquids at Room Temperature. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800771] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Carsten Donsbach
- Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW) Philipps‐Universität Marburg Hans‐Meerwein‐Straße 4 35043 Marburg Germany
| | - Stefanie Dehnen
- Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW) Philipps‐Universität Marburg Hans‐Meerwein‐Straße 4 35043 Marburg Germany
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14
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Rico del Cerro D, Mera‐Adasme R, King AWT, Perea‐Buceta JE, Heikkinen S, Hase T, Sundholm D, Wähälä K. On the Mechanism of the Reactivity of 1,3‐Dialkylimidazolium Salts under Basic to Acidic Conditions: A Combined Kinetic and Computational Study. Angew Chem Int Ed Engl 2018; 57:11613-11617. [PMID: 29987916 DOI: 10.1002/anie.201805016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/07/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Daniel Rico del Cerro
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Raúl Mera‐Adasme
- Departamento de Ciencias del AmbienteFacultad de Química y BiologíaUniversidad de Santiago de Chile Av. Libertador Bernardo O'Higgins 3363 9170022 Estacion Central Chile
| | - Alistair W. T. King
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Jesus E. Perea‐Buceta
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Sami Heikkinen
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Tapio Hase
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Dage Sundholm
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Kristiina Wähälä
- Department of ChemistryUniversity of Helsinki P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
- Department of Biochemistry and Development BiologyUniversity of Helsinki Haartmaninkatu 3, P.O. Box 21 000140 Helsinki Finland
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15
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Rico del Cerro D, Mera-Adasme R, King AWT, Perea-Buceta JE, Heikkinen S, Hase T, Sundholm D, Wähälä K. On the Mechanism of the Reactivity of 1,3-Dialkylimidazolium Salts under Basic to Acidic Conditions: A Combined Kinetic and Computational Study. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Daniel Rico del Cerro
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Raúl Mera-Adasme
- Departamento de Ciencias del Ambiente; Facultad de Química y Biología; Universidad de Santiago de Chile; Av. Libertador Bernardo O'Higgins 3363 9170022 Estacion Central Chile
| | - Alistair W. T. King
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Jesus E. Perea-Buceta
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Sami Heikkinen
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Tapio Hase
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Dage Sundholm
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Kristiina Wähälä
- Department of Chemistry; University of Helsinki; P.O. Box 55, A.I. Virtasen aukio 1 00014 Helsinki Finland
- Department of Biochemistry and Development Biology; University of Helsinki; Haartmaninkatu 3, P.O. Box 21 000140 Helsinki Finland
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16
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Chiarotto I, Mattiello L, Pandolfi F, Rocco D, Feroci M. NHC in Imidazolium Acetate Ionic Liquids: Actual or Potential Presence? Front Chem 2018; 6:355. [PMID: 30211149 PMCID: PMC6121013 DOI: 10.3389/fchem.2018.00355] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 07/30/2018] [Indexed: 11/13/2022] Open
Abstract
Ionic liquids (ILs) are considered in the majority of cases green solvents, due to their virtually null vapor pressure and to the easiness in recycling them. In particular, imidazolium ILs are widely used in many fields of Chemistry, as solvents or precursors of N-heterocyclic carbenes (NHCs). The latter are easily obtained by deprotonation of the C2-H, usually using strong bases or cathodic reduction. Nevertheless, it is known that weaker bases (e.g., triethylamine) are able to promote C2-H/D exchange. From this perspective, the possibility of deprotonating C2-H group of an imidazolium cation by means of a basic counter-ion was seriously considered and led to the synthesis of imidazolium ILs spontaneously containing NHCs. The most famous of this class of ILs are N,N'-disubstituted imidazolium acetates. Due to the particular reactivity of this kind of ILs, they were appointed as “organocatalytic ionic liquids” or “proto-carbenes.” Many papers report the use of these imidazolium acetates in organocatalytic reactions (i. e., catalyzed by NHC) or in stoichiometric NHC reactions (e.g., with elemental sulfur to yield the corresponding imidazole-2-thiones). Nevertheless, the actual presence of NHC in N,N'-disubstituted imidazolium acetate is still controversial. Moreover, theoretical studies seem to rule out the presence of NHC in such a polar environment as an IL. Aim of this Mini Review is to give the reader an up-to-date overview on the actual or potential presence of NHC in such an “organocatalytic ionic liquid,” both from the experimental and theoretical point of view, without the intent to be exhaustive on N,N'-disubstituted imidazolium acetate applications.
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Affiliation(s)
- Isabella Chiarotto
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
| | - Leonardo Mattiello
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
| | - Fabiana Pandolfi
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
| | - Daniele Rocco
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
| | - Marta Feroci
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
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17
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Doherty B, Zhong X, Acevedo O. Virtual Site OPLS Force Field for Imidazolium-Based Ionic Liquids. J Phys Chem B 2018; 122:2962-2974. [DOI: 10.1021/acs.jpcb.7b11996] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian Doherty
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Xiang Zhong
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Orlando Acevedo
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
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18
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Michez R, Doneux T, Buess-Herman C, Luhmer M. NMR Study of the Reductive Decomposition of [BMIm][NTf 2 ] at Gold Electrodes and Indirect Electrochemical Conversion of CO 2. Chemphyschem 2017. [PMID: 28631384 DOI: 10.1002/cphc.201700421] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Potential controlled electrolyses of [BMIm][NTf2 ] ionic liquid were performed at a gold cathode under nitrogen atmosphere. The structures of the major conversion products of the BMIm+ cation were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) analyses and gas chromatography (GC) analysis of the volatile compounds. Recombination of the imidazol-2-yl radicals, generated at the electrode by single electron transfer, leads to neutral diastereomeric dimers in equal proportions, with a faradaic efficiency of 80 %, while disproportionation of these radicals and/or reaction with hydrogen atoms adsorbed at the electrode generates a neutral monomer with 20 % faradaic efficiency. Both pathways also yield the N-heterocyclic carbene imidazolin-2-ylidene, which is involved in fast proton exchange with the parent BMIm+ cation. The reductive decomposition products of the BMIm+ cation are no longer detected if the pre-electrolysed sample is reacted with CO2 , which undergoes an indirect reduction and generates the carboxylate adduct.
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Affiliation(s)
- Roman Michez
- Service de Chimie Analytique et Chimie des Interfaces, CP 255 Faculté des Sciences, Université libre de Bruxelles, 2, Boulevard du Triomphe, 1050, Bruxelles, Belgium
| | - Thomas Doneux
- Service de Chimie Analytique et Chimie des Interfaces, CP 255 Faculté des Sciences, Université libre de Bruxelles, 2, Boulevard du Triomphe, 1050, Bruxelles, Belgium
| | - Claudine Buess-Herman
- Service de Chimie Analytique et Chimie des Interfaces, CP 255 Faculté des Sciences, Université libre de Bruxelles, 2, Boulevard du Triomphe, 1050, Bruxelles, Belgium
| | - Michel Luhmer
- Laboratoire de Résonance Magnétique Nucléaire Haute Résolution, CP 160/08, Faculté des Sciences, Université libre de Bruxelles, 50, avenue F.-D. Roosevelt, 1050, Bruxelles, Belgium
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19
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Gehrke S, Schmitz K, Hollóczki O. Is Carbene Formation Necessary for Dissolving Cellulose in Ionic Liquids? J Phys Chem B 2017; 121:4521-4529. [DOI: 10.1021/acs.jpcb.7b00631] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sascha Gehrke
- Mulliken
Center for Theoretical Chemistry, University of Bonn, Beringstr. 4 + 6, D-53115 Bonn, Germany
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Muelheim an der Ruhr, Germany
| | - Karola Schmitz
- Mulliken
Center for Theoretical Chemistry, University of Bonn, Beringstr. 4 + 6, D-53115 Bonn, Germany
| | - Oldamur Hollóczki
- Mulliken
Center for Theoretical Chemistry, University of Bonn, Beringstr. 4 + 6, D-53115 Bonn, Germany
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20
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Shojaei S, Ghasemi Z, Shahrisa A. Cu(I)@Fe
3
O
4
nanoparticles supported on imidazolium‐based ionic liquid‐grafted cellulose: Green and efficient nanocatalyst for multicomponent synthesis of
N
‐sulfonylamidines and
N
‐sulfonylacrylamidines. Appl Organomet Chem 2017. [DOI: 10.1002/aoc.3788] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Salman Shojaei
- Department of Organic and Biochemistry, Faculty of ChemistryUniversity of Tabriz Tabriz 5166614766 Iran
| | - Zarrin Ghasemi
- Department of Organic and Biochemistry, Faculty of ChemistryUniversity of Tabriz Tabriz 5166614766 Iran
| | - Aziz Shahrisa
- Department of Organic and Biochemistry, Faculty of ChemistryUniversity of Tabriz Tabriz 5166614766 Iran
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21
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Ullah B, Chen J, Zhang Z, Xing H, Yang Q, Bao Z, Ren Q. 1-Ethyl-3-methylimidazolium acetate as a highly efficient organocatalyst for cyanosilylation of carbonyl compounds with trimethylsilyl cyanide. Sci Rep 2017; 7:42699. [PMID: 28198462 PMCID: PMC5309884 DOI: 10.1038/srep42699] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/21/2016] [Indexed: 01/31/2023] Open
Abstract
1-Ethyl-3-methylimidazolium acetate is introduced as a robust organocatalyst for solvent-free cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (TMSCN). The catalyst loading can be reduced to as low as 0.1–0.0001 mol % under mild reaction conditions, giving considerably high TOF values from 10,843 h−1 to 10,602,410 h−1 in the field of organocatalyzed transformations. The present protocol not only tolerates with extensive carbonyl compounds but also provides somewhat insight into the mechanism of ionic liquids (ILs)-catalyzed reactions.
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Affiliation(s)
- Bakhtar Ullah
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jingwen Chen
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Zhiguo Zhang
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Huabin Xing
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Qiwei Yang
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Zongbi Bao
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Qilong Ren
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
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22
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Izgorodina EI, Seeger ZL, Scarborough DLA, Tan SYS. Quantum Chemical Methods for the Prediction of Energetic, Physical, and Spectroscopic Properties of Ionic Liquids. Chem Rev 2017; 117:6696-6754. [PMID: 28139908 DOI: 10.1021/acs.chemrev.6b00528] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The accurate prediction of physicochemical properties of condensed systems is a longstanding goal of theoretical (quantum) chemistry. Ionic liquids comprising entirely of ions provide a unique challenge in this respect due to the diverse chemical nature of available ions and the complex interplay of intermolecular interactions among them, thus resulting in the wide variability of physicochemical properties, such as thermodynamic, transport, and spectroscopic properties. It is well understood that intermolecular forces are directly linked to physicochemical properties of condensed systems, and therefore, an understanding of this relationship would greatly aid in the design and synthesis of functionalized materials with tailored properties for an application at hand. This review aims to give an overview of how electronic structure properties obtained from quantum chemical methods such as interaction/binding energy and its fundamental components, dipole moment, polarizability, and orbital energies, can help shed light on the energetic, physical, and spectroscopic properties of semi-Coulomb systems such as ionic liquids. Particular emphasis is given to the prediction of their thermodynamic, transport, spectroscopic, and solubilizing properties.
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Affiliation(s)
- Ekaterina I Izgorodina
- Monash Computational Chemistry Group, School of Chemistry, Monash University , 17 Rainforest Walk, Clayton, Victoria 3800, Australia
| | - Zoe L Seeger
- Monash Computational Chemistry Group, School of Chemistry, Monash University , 17 Rainforest Walk, Clayton, Victoria 3800, Australia
| | - David L A Scarborough
- Monash Computational Chemistry Group, School of Chemistry, Monash University , 17 Rainforest Walk, Clayton, Victoria 3800, Australia
| | - Samuel Y S Tan
- Monash Computational Chemistry Group, School of Chemistry, Monash University , 17 Rainforest Walk, Clayton, Victoria 3800, Australia
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23
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Chiarotto I, Feroci M, Inesi A. First direct evidence of N-heterocyclic carbene in BMIm acetate ionic liquids. An electrochemical and chemical study on the role of temperature. NEW J CHEM 2017. [DOI: 10.1039/c7nj00779e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cyclic voltammetry measurements provide the first direct evidence of N-heterocyclic carbene in neat 1-butyl-3-methylimidazolium acetate ionic liquid at temperatures over 120 °C.
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Affiliation(s)
- I. Chiarotto
- Dept. SBAI, Sapienza University of Rome
- 00161 Rome
- Italy
| | - M. Feroci
- Dept. SBAI, Sapienza University of Rome
- 00161 Rome
- Italy
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24
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Firaha DS, Thomas M, Hollóczki O, Korth M, Kirchner B. Can dispersion corrections annihilate the dispersion-driven nano-aggregation of non-polar groups? An ab initio molecular dynamics study of ionic liquid systems. J Chem Phys 2016; 145:204502. [DOI: 10.1063/1.4967861] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Dzmitry S. Firaha
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - Martin Thomas
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - Martin Korth
- Institut für Theoretische Chemie, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
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25
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Advances in the Knowledge of N-Heterocyclic Carbenes Properties. The Backing of the Electrochemical Investigation. Catalysts 2016. [DOI: 10.3390/catal6110178] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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26
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N-Heterocyclic Carbenes and Parent Cations: Acidity, Nucleophilicity, Stability, and Hydrogen Bonding-Electrochemical Study and Ab Initio Calculations. ChemElectroChem 2016. [DOI: 10.1002/celc.201600187] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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27
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The synergistic effect of copper chromite spinel nanoparticles (CuCr2O4) and basic ionic liquid on the synthesis of cyclopropanecarboxylic acids. RESEARCH ON CHEMICAL INTERMEDIATES 2016. [DOI: 10.1007/s11164-016-2572-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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28
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Hollóczki O. Unveiling the peculiar hydrogen bonding behavior of solvated N-heterocyclic carbenes. Phys Chem Chem Phys 2016; 18:126-40. [DOI: 10.1039/c5cp05369b] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
After fitting a molecular mechanical force field for imidazol-2-ylidenes, MD simulations revealed carbene–carbene and three-center hydrogen bonds of carbenes. The practical importance of these structures is also highlighted.
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Affiliation(s)
- Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry
- University of Bonn
- D-53115 Bonn
- Germany
- Department of Inorganic and Analytical Chemistry
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29
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Yao Y, Li Y, Liu X, Zhang X, Wang J, Yao X, Zhang S. Mechanistic study on the cellulose dissolution in ionic liquids by density functional theory. Chin J Chem Eng 2015. [DOI: 10.1016/j.cjche.2015.07.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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30
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Kar BP, Sander W. Reversible Carbene Formation in the Ionic Liquid 1-Ethyl-3-Methylimidazolium Acetate by Vaporization and Condensation. Chemphyschem 2015; 16:3603-6. [DOI: 10.1002/cphc.201500729] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Bishnu Prasad Kar
- Lehrstuhl für Organische Chemie II; Ruhr-Universität Bochum; 44780 Bochum Germany
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II; Ruhr-Universität Bochum; 44780 Bochum Germany
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31
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Chiarotto I, Feroci M, Forte G, Inesi A. Stability of electrogenerated 1-butyl-3-methylimidazol-2-ylidene in DMF. Part 2. Role of acid substrates. [1]. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.06.129] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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32
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Affiliation(s)
- Robert Hayes
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Gregory G. Warr
- School
of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia
| | - Rob Atkin
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
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33
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Abstract
Ionic liquids (IL) and hydrogen bonding (H-bonding) are two diverse fields for which there is a developing recognition of significant overlap. Doubly ionic H-bonds occur when a H-bond forms between a cation and anion, and are a key feature of ILs. Doubly ionic H-bonds represent a wide area of H-bonding which has yet to be fully recognised, characterised or explored. H-bonds in ILs (both protic and aprotic) are bifurcated and chelating, and unlike many molecular liquids a significant variety of distinct H-bonds are formed between different types and numbers of donor and acceptor sites within a given IL. Traditional more neutral H-bonds can also be formed in functionalised ILs, adding a further level of complexity. Ab initio computed parameters; association energies, partial charges, density descriptors as encompassed by the QTAIM methodology (ρBCP), qualitative molecular orbital theory and NBO analysis provide established and robust mechanisms for understanding and interpreting traditional neutral and ionic H-bonds. In this review the applicability and extension of these parameters to describe and quantify the doubly ionic H-bond has been explored. Estimating the H-bonding energy is difficult because at a fundamental level the H-bond and ionic interaction are coupled. The NBO and QTAIM methodologies, unlike the total energy, are local descriptors and therefore can be used to directly compare neutral, ionic and doubly ionic H-bonds. The charged nature of the ions influences the ionic characteristics of the H-bond and vice versa, in addition the close association of the ions leads to enhanced orbital overlap and covalent contributions. The charge on the ions raises the energy of the Ylp and lowers the energy of the X-H σ* NBOs resulting in greater charge transfer, strengthening the H-bond. Using this range of parameters and comparing doubly ionic H-bonds to more traditional neutral and ionic H-bonds it is clear that doubly ionic H-bonds cover the full range of weak through to very strong H-bonds.
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Affiliation(s)
- Patricia A Hunt
- Department of Chemistry, Faculty of Natural Sciences, Imperial College London, London, SW7 2AZ, UK.
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34
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Thomas M, Brehm M, Hollóczki O, Kelemen Z, Nyulászi L, Pasinszki T, Kirchner B. Simulating the vibrational spectra of ionic liquid systems: 1-ethyl-3-methylimidazolium acetate and its mixtures. J Chem Phys 2015; 141:024510. [PMID: 25028030 DOI: 10.1063/1.4887082] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The vibrational spectra of the ionic liquid 1-ethyl-3-methylimidazolium acetate and its mixtures with water and carbon dioxide are calculated using ab initio molecular dynamics simulations, and the results are compared to experimental data. The new implementation of a normal coordinate analysis in the trajectory analyzer TRAVIS is used to assign the experimentally observed bands to specific molecular vibrations. The applied computational approaches prove to be particularly suitable for the modeling of bulk phase effects on vibrational spectra, which are highly important for the discussion of the microscopic structure in systems with a strong dynamic network of intermolecular interactions, such as ionic liquids.
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Affiliation(s)
- Martin Thomas
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstraße 4, 53115 Bonn, Germany
| | - Martin Brehm
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Linnéstraße 2, 04103 Leipzig, Germany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstraße 4, 53115 Bonn, Germany
| | - Zsolt Kelemen
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, 1111 Budapest, Hungary
| | - László Nyulászi
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, 1111 Budapest, Hungary
| | - Tibor Pasinszki
- Department of Inorganic Chemistry, Institute of Chemistry, Eötvös Loránd University, Pázmány P. sétány 1/A, 1117 Budapest, Hungary
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstraße 4, 53115 Bonn, Germany
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35
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Hollóczki O, Malberg F, Welton T, Kirchner B. On the origin of ionicity in ionic liquids. Ion pairing versus charge transfer. Phys Chem Chem Phys 2015; 16:16880-90. [PMID: 25012230 DOI: 10.1039/c4cp01177e] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this paper we show by using static DFT calculations and classical molecular dynamics simulations that the charge transfer between ionic liquid ions plays a major role in the observed discrepancies between the overall mobility of the ions and the observed conductivities of the corresponding ionic liquids, while it also directly suppresses the association of oppositely charged ions, thus the ion pairing. Accordingly, in electrochemical applications of these materials it is important to consider this reduction of the total charges on the ions, which can greatly affect the performance of the given process or device in which the ionic liquid is used. By slightly shifting from the salt-like to a molecular liquid-like system via the decreased charges, the charge transfer also fluidizes the ionic liquid. We believe that this vital information on the molecular level structure of ionic liquids offers a better understanding of these materials, and allows us to improve the a priori design of ionic liquids for any given purpose.
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Affiliation(s)
- Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, D-53115 Bonn, Germany.
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36
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Stability and organocatalytic efficiency of N-heterocyclic carbenes electrogenerated in organic solvents from imidazolium ionic liquids. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2014.11.135] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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37
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Kirchner B, Hollóczki O, Canongia Lopes JN, Pádua AAH. Multiresolution calculation of ionic liquids. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2014. [DOI: 10.1002/wcms.1212] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Barbara Kirchner
- Mulliken Center for Theoretical Chemistry; Rheinische Friedrich-Wilhelms-Universität Bonn; Bonn Germany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry; Rheinische Friedrich-Wilhelms-Universität Bonn; Bonn Germany
| | - José Nuno Canongia Lopes
- Centro de Química Estrutural, Instituto Superior Técnico; Universidade de Lisboa; Lisboa Portugal
- Instituto de Tecnologia Química e Biológica; Universidade Nova de Lisboa; Lisboa Portugal
| | - Agílio A. H. Pádua
- Institut de Chimie de Clermont-Ferrand; Université Blaise Pascal and CNRS; Clermont-Ferrand France
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38
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Ta L, Axelsson A, Bijl J, Haukka M, Sundén H. Ionic liquids as precatalysts in the highly stereoselective conjugate addition of α,β-unsaturated aldehydes to chalcones. Chemistry 2014; 20:13889-93. [PMID: 25201607 DOI: 10.1002/chem.201404288] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Indexed: 11/06/2022]
Abstract
Imidazolium-based ionic liquids (ILs) serve both as recyclable reaction media and as precatalysts for the N-heterocyclic carbene-catalyzed conjugate addition of α,β-unsaturated aldehydes to chalcones. The reaction produces a broad scope of 1,6-ketoesters incorporating an anti-diphenyl moiety in high yields and with high stereoselectivity. In recycling experiments, the IL can be reused up to five times with retained reactivity and selectivity. Moreover, the 1,6-ketoesters form self-assembled organogels in aliphatic hydrocarbons. The reaction protocol is robust, easily operated, scalable and highly functionalized compounds can be obtained from inexpensive and readily accessible starting materials.
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Affiliation(s)
- Linda Ta
- Chemistry and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg (Sweden)
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39
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Kelemen Z, Péter-Szabó B, Székely E, Hollóczki O, Firaha DS, Kirchner B, Nagy J, Nyulászi L. An abnormal N-heterocyclic carbene-carbon dioxide adduct from imidazolium acetate ionic liquids: the importance of basicity. Chemistry 2014; 20:13002-8. [PMID: 25137312 DOI: 10.1002/chem.201402912] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Indexed: 11/08/2022]
Abstract
In the reaction of 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc] ionic liquid with carbon dioxide at 125 °C and 10 MPa, not only the known N-heterocyclic carbene (NHC)-CO2 adduct I, but also isomeric aNHC-CO2 adducts II and III were obtained. The abnormal NHC-CO2 adducts are stabilized by the presence of the polarizing basic acetate anion, according to static DFT calculations and ab initio molecular dynamics studies. A further possible reaction pathway is facilitated by the high basicity of the system, deprotonating the initially formed NHC-CO2 adduct I, which can then be converted in the presence of the excess of CO2 to the more stable 2-deprotonated anionic abnormal NHC-CO2 adduct via the anionic imidazolium-2,4-dicarboxylate according to DFT calculations on model compounds. This suggests a generalizable pathway to abnormal NHC complex formation.
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Affiliation(s)
- Zsolt Kelemen
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4. Budapest, 1111 (Hungary)
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Cabaço MI, Besnard M, Chávez FV, Pinaud N, Sebastião PJ, Coutinho JAP, Danten Y. Understanding chemical reactions of CO2and its isoelectronic molecules with 1-butyl-3-methylimidazolium acetate by changing the nature of the cation: The case of CS2in 1-butyl-1-methylpyrrolidinium acetate studied by NMR spectroscopy and density functional theory calculations. J Chem Phys 2014; 140:244307. [DOI: 10.1063/1.4884820] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Hollóczki O. Uranyl(VI) Complexes in and from Imidazolium Acetate Ionic Liquids: Carbenes versus Acetates? Inorg Chem 2013; 53:835-46. [DOI: 10.1021/ic402921b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Oldamur Hollóczki
- Mulliken
Center for Theoretical Chemistry, University of Bonn, Beringstrasse
4 + 6, D-53115 Bonn, Germany
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