1
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Wegener D, Pérez-Bitrián A, Limberg N, Wiesner A, Hoffmann KF, Riedel S. A Highly Sterically Encumbered Boron Lewis Acid Enabled by an Organotellurium-Based Ligand. Chemistry 2024; 30:e202401231. [PMID: 38625061 DOI: 10.1002/chem.202401231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/17/2024]
Abstract
Lewis acidic boron compounds are ubiquitous in chemistry due to their numerous applications, yet tuning and optimizing their properties towards different purposes is still a challenging field of research. In this work, the boron-based Lewis acid B[OTeF3(C6F5)2]3 was synthesized by reaction of the teflate derivative HOTeF3(C6F5)2 with BCl3 or BCl3 ⋅ SMe2. This new compound presents a remarkably high thermal stability up to 300 °C, as well as one of the most sterically encumbered boron centres known in the literature. Theoretical and experimental methods revealed that B[OTeF3(C6F5)2]3 exhibits a comparable Lewis acidity to that of the well-known B(C6F5)3. The affinity of B[OTeF3(C6F5)2]3 towards pyridine was accessed by Isothermal Titration Calorimetry (ITC) and compared to that of B(OTeF5)3 and B(C6F5)3. The ligand-transfer reactivity of this new boron compound towards different fluorides was demonstrated by the formation of an anionic Au(III) complex and a hypervalent iodine(III) species.
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Affiliation(s)
- Daniel Wegener
- Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie - Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
| | - Alberto Pérez-Bitrián
- Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie - Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
- Current address: Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489, Berlin, Germany
| | - Niklas Limberg
- Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie - Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
| | - Anja Wiesner
- Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie - Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
| | - Kurt F Hoffmann
- Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie - Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
| | - Sebastian Riedel
- Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie - Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
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2
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Erdmann P, Schmitt M, Sigmund LM, Krämer F, Breher F, Greb L. How to Deal with Charge in the Ranking of Lewis Acidity: Critical Evaluation of an Extensive Set of Cationic Lewis Acids. Angew Chem Int Ed Engl 2024; 63:e202403356. [PMID: 38478925 DOI: 10.1002/anie.202403356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Indexed: 04/09/2024]
Abstract
The quantification of Lewis acidity is of fundamental and applied importance in chemistry. However, if neutral and charged Lewis acids are compared, a coherent ranking has been elusive, and severe uncertainties were accepted. With this study, we present a systematic computational analysis of Lewis base affinities of 784 mono-, di- and tricationic Lewis acids and their comparison with 149 representative neutral Lewis acids. Evaluating vacuum fluoride ion affinities (FIA) reveals a charge-caused clustering that prohibits any meaningful ranking. Instead, solvation-corrected FIAsolv is identified as a metric that overcomes charge sensitivity in a balanced manner, allowing for a coherent evaluation of Lewis acidity across varying charge states. Analyzing the impact of molecular volume on solvation-induced FIA damping provides rationales for fundamental trends and guidelines for the choice or design of neutral and cationic Lewis acids in the condensed phase. Exploring alternative scales, explicit counteranion effects, and selected experimental case studies reaffirms the advantages of solvation-corrected FIAsolv as the most versatile and practical approach for the quantitative ranking of general (thermodynamic) Lewis acidity.
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Affiliation(s)
- Philipp Erdmann
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Manuel Schmitt
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Lukas M Sigmund
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Felix Krämer
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| | - Frank Breher
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| | - Lutz Greb
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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3
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Saida AB, Mahaut D, Tumanov N, Wouters J, Champagne B, Vanthuyne N, Robiette R, Berionni G. Reactivity and Steric Parameters from 2D to 3D Bulky Pyridines: Increasing Steric Demand at Nitrogen with Chiral Azatriptycenes. Angew Chem Int Ed Engl 2024:e202407503. [PMID: 38781114 DOI: 10.1002/anie.202407503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 05/25/2024]
Abstract
Sterically hindered pyridines embedded in a three-dimensional triptycene framework have been synthesized, and their resolution by chiral HPLC enabled access to unprecedented enantiopure pyridines exceeding the known steric limits. The design principles for new axially chiral pyridine derivatives are then described. To rationalize their associations with Lewis acids and transition metals, a comprehensive determination of the steric and electronic parameters for this new class of pyridines was performed. This led to the general parameterization of the steric parameters (percent buried volume %VBur, Tolman cone angle θ, and He8_steric descriptor) for a large set of two- and three-dimensional pyridine derivatives. These parameters are shown to describe quantitatively their interactions with carbon- and boron-centered Lewis acids and were used to predict the ΔG° of association with the prototypical B(C6F5)3 Lewis acid widely used in frustrated Lewis pair catalysis. This first parameterization of pyridine sterics is a fundamental basis for the future development of predictive reactivity models and for guiding new applications of bulky and chiral pyridines in organocatalysis, frustrated Lewis pairs, and transition-metal catalysis.
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Affiliation(s)
- Ali Ben Saida
- Department of Chemistry and Namur Institute of Structured Matter, Université de Namur, 61 Rue de Bruxelles, 5000, Namur, Belgium
| | - Damien Mahaut
- Department of Chemistry and Namur Institute of Structured Matter, Université de Namur, 61 Rue de Bruxelles, 5000, Namur, Belgium
| | - Nikolay Tumanov
- Department of Chemistry and Namur Institute of Structured Matter, Université de Namur, 61 Rue de Bruxelles, 5000, Namur, Belgium
| | - Johan Wouters
- Department of Chemistry and Namur Institute of Structured Matter, Université de Namur, 61 Rue de Bruxelles, 5000, Namur, Belgium
| | - Benoît Champagne
- Department of Chemistry and Namur Institute of Structured Matter, Université de Namur, 61 Rue de Bruxelles, 5000, Namur, Belgium
| | - Nicolas Vanthuyne
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Raphaël Robiette
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Place Louis Pasteur 1 Box L4.01.02, 1348, Louvain-la-Neuve, Belgium
| | - Guillaume Berionni
- Department of Chemistry and Namur Institute of Structured Matter, Université de Namur, 61 Rue de Bruxelles, 5000, Namur, Belgium
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4
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Sigmund LM, S SS, Albers A, Erdmann P, Paton RS, Greb L. Predicting Lewis Acidity: Machine Learning the Fluoride Ion Affinity of p-Block-Atom-Based Molecules. Angew Chem Int Ed Engl 2024; 63:e202401084. [PMID: 38452299 DOI: 10.1002/anie.202401084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 03/09/2024]
Abstract
"How strong is this Lewis acid?" is a question researchers often approach by calculating its fluoride ion affinity (FIA) with quantum chemistry. Here, we present FIA49k, an extensive FIA dataset with 48,986 data points calculated at the RI-DSD-BLYP-D3(BJ)/def2-QZVPP//PBEh-3c level of theory, including 13 different p-block atoms as the fluoride accepting site. The FIA49k dataset was used to train FIA-GNN, two message-passing graph neural networks, which predict gas and solution phase FIA values of molecules excluded from training with a mean absolute error of 14 kJ mol-1 (r2=0.93) from the SMILES string of the Lewis acid as the only input. The level of accuracy is notable, given the wide energetic range of 750 kJ mol-1 spanned by FIA49k. The model's value was demonstrated with four case studies, including predictions for molecules extracted from the Cambridge Structural Database and by reproducing results from catalysis research available in the literature. Weaknesses of the model are evaluated and interpreted chemically. FIA-GNN and the FIA49k dataset can be reached via a free web app (www.grebgroup.de/fia-gnn).
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Affiliation(s)
- Lukas M Sigmund
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
- Department of Chemistry, Colorado State University, 1301 Center Avenue, Fort Collins, CO, 80523, USA
| | - Shree Sowndarya S
- Department of Chemistry, Colorado State University, 1301 Center Avenue, Fort Collins, CO, 80523, USA
| | - Andreas Albers
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Philipp Erdmann
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Robert S Paton
- Department of Chemistry, Colorado State University, 1301 Center Avenue, Fort Collins, CO, 80523, USA
| | - Lutz Greb
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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5
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Kótai B, Laczkó G, Hamza A, Pápai I. Stereocontrol via Propeller Chirality in FLP-Catalyzed Asymmetric Hydrogenation. Chemistry 2024; 30:e202400241. [PMID: 38294415 DOI: 10.1002/chem.202400241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/01/2024]
Abstract
Utilization of chiral frustrated Lewis pairs as catalysts in enantioselective hydrogenation of unsaturated molecules represents a promising approach in asymmetric synthesis. In our effort to improve our current understanding of the factors governing the stereoselectivity in these catalytic processes, herein we examined the mechanism of direct hydrogenation of aromatic enamines catalyzed by a binaphthyl-based chiral amino-borane. Our computational analysis reveals that only one particular conformer of the key borohydride reaction intermediate can be regarded as a reactive form of this species. This borohydride conformer has a well-defined chiral propeller shape, which induces facial selectivity in the hydride transfer to pro-chiral iminium intermediates. The propeller chirality of the reactive borohydride conformer is generated by the axially chiral binaphthyl scaffold of the amino-borane catalyst through stabilizing π-π stacking interactions. This new computational insight can be readily used to interpret the high degree of stereoinduction observed for these reactions. We expect that the concept of chirality relay could be further exploited in catalyst design endeavors.
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Affiliation(s)
- B Kótai
- Institute of Organic Chemistry, Research Centre for Natural Sciences, H-1117, Budapest, Magyar tudósok körútja 2
- Hevesy György Ph.D. School of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518, Budapest, Hungary
| | - G Laczkó
- Institute of Organic Chemistry, Research Centre for Natural Sciences, H-1117, Budapest, Magyar tudósok körútja 2
- Hevesy György Ph.D. School of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518, Budapest, Hungary
| | - A Hamza
- Institute of Organic Chemistry, Research Centre for Natural Sciences, H-1117, Budapest, Magyar tudósok körútja 2
| | - I Pápai
- Institute of Organic Chemistry, Research Centre for Natural Sciences, H-1117, Budapest, Magyar tudósok körútja 2
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6
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Escayola S, Bahri-Laleh N, Poater A. % VBur index and steric maps: from predictive catalysis to machine learning. Chem Soc Rev 2024; 53:853-882. [PMID: 38113051 DOI: 10.1039/d3cs00725a] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Steric indices are parameters used in chemistry to describe the spatial arrangement of atoms or groups of atoms in molecules. They are important in determining the reactivity, stability, and physical properties of chemical compounds. One commonly used steric index is the steric hindrance, which refers to the obstruction or hindrance of movement in a molecule caused by bulky substituents or functional groups. Steric hindrance can affect the reactivity of a molecule by altering the accessibility of its reactive sites and influencing the geometry of its transition states. Notably, the Tolman cone angle and %VBur are prominent among these indices. Actually, steric effects can also be described using the concept of steric bulk, which refers to the space occupied by a molecule or functional group. Steric bulk can affect the solubility, melting point, boiling point, and viscosity of a substance. Even though electronic indices are more widely used, they have certain drawbacks that might shift preferences towards others. They present a higher computational cost, and often, the weight of electronics in correlation with chemical properties, e.g. binding energies, falls short in comparison to %VBur. However, it is worth noting that this may be because the steric index inherently captures part of the electronic content. Overall, steric indices play an important role in understanding the behaviour of chemical compounds and can be used to predict their reactivity, stability, and physical properties. Predictive chemistry is an approach to chemical research that uses computational methods to anticipate the properties and behaviour of these compounds and reactions, facilitating the design of new compounds and reactivities. Within this domain, predictive catalysis specifically targets the prediction of the performance and behaviour of catalysts. Ultimately, the goal is to identify new catalysts with optimal properties, leading to chemical processes that are both more efficient and sustainable. In this framework, %VBur can be a key metric for deepening our understanding of catalysis, emphasizing predictive catalysis and sustainability. Those latter concepts are needed to direct our efforts toward identifying the optimal catalyst for any reaction, minimizing waste, and reducing experimental efforts while maximizing the efficacy of the computational methods.
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Affiliation(s)
- Sílvia Escayola
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, c/Mª Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
- Donostia International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
| | - Naeimeh Bahri-Laleh
- Iran Polymer and Petrochemical Institute (IPPI), P.O. Box 14965/115, Tehran, Iran
- Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, Hiroshima, 739-8526, Japan
| | - Albert Poater
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, c/Mª Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
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7
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Timoshkin AY. The Field of Main Group Lewis Acids and Lewis Superacids: Important Basics and Recent Developments. Chemistry 2024; 30:e202302457. [PMID: 37752859 DOI: 10.1002/chem.202302457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 09/28/2023]
Abstract
New developments in the field of Lewis acidity are highlighted, with the focus of novel Lewis acids and Lewis superacids of group 2, 13, 14, and 15 elements. Several important basics, illustrated by modern examples (classification of Donor-Acceptor (DA) complexes, amphoteric nature of any compound in terms of DA interactions, reorganization energies of main group Lewis acids and the role of the energies of frontier orbitals) are presented and discussed. It is emphasized that the Lewis acidity phenomena are general and play vital role in different areas of chemistry: from weak "atomophilic" interactions to the complexes of Lewis superacids.
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Affiliation(s)
- Alexey Y Timoshkin
- Institute of Chemistry, St. Petersburg State University, 199034, Universitetskaya emb. 7/9, St. Petersburg, Russia
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8
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Bischof T, Wieprecht N, Fuchs S, Endres L, Krummenacher I, Michel M, Mihm C, Braunschweig H, Finze M. Unlocking Heteroaromatic Ring Systems through Chalcogen Insertion into Boroles. Inorg Chem 2023; 62:21329-21335. [PMID: 38048693 DOI: 10.1021/acs.inorgchem.3c03403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
In this work, we report the reactivity of various annulated borole derivatives toward chalcogen (O, S, and Se) insertion. Among a series of 9-borafluorenes with different boron substituents (Ph, Br, or o-carboranyl) and a mixed thiophene-benzene-fused derivative, only the 9-o-carboranyl-substituted 9-borafluorene yielded the complete set of chalcogen-containing heteroarenes, including the first 1,2-selenaborinine derivative. To evaluate the aromaticity of this heterocyclic analogue of phenanthrene, nucleus-independent chemical shift (NICS) values were computed and compared to those of its lighter group 16 congeners.
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Affiliation(s)
- Tobias Bischof
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Nele Wieprecht
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Sonja Fuchs
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Lukas Endres
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Maximilian Michel
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Cornelius Mihm
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Maik Finze
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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9
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Werner L, Hagn J, Radius U. NHC-Stabilized Dialanes(4) of Al 2 Mes 4. Chemistry 2023; 29:e202303111. [PMID: 37792718 DOI: 10.1002/chem.202303111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 09/29/2023] [Accepted: 10/02/2023] [Indexed: 10/06/2023]
Abstract
The synthesis and characterization of novel N-heterocyclic carbene (NHC) stabilized dialanes Al2 Mes4 as well as first investigations concerning the reactivity of these compounds are reported. The synthesis of these compounds proceeds via the mesityl-substituted alanes (NHC)⋅AlHMes2 (NHC=IMeMe {=1,3,4,5-tetramethyl-imidazolin-2-ylidene}, IiPrMe {=1,3-di-iso-propyl-4,5-dimethylimidazolin-2-ylidene}) and iodo-alanes (NHC)⋅AlIMes2 (NHC=IMeMe , IiPrMe ). Metallic reduction of (NHC)⋅AlIMes2 afforded the new NHC-stabilized dialanes (NHC)2 ⋅Al2 Mes4 (NHC=IMeMe , IiPrMe ). The NHC-ligated dialanes are thermally robust and storable synthons for the dialane Al2 Mes4 . First reactivity studies on (IMeMe )2 ⋅Al2 Mes4 towards small molecules confirm this, as this compound shows controlled and selective reactions with several substrates. Reaction with CuCl leads to oxidation of the dialane and formation of (IMeMe )⋅AlClMes2 , reactions with pyridine N-oxide and t Bu-N=C=S, respectively, gave the chalcogenide-bridged dimers {(IMeMe )⋅AlMes2 }2 -μ-E (E=O, S), and reaction with acetylene afforded the dimetallaacetylide {(IMeMe )⋅AlMes2 }2 -μ-(C≡C).
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Affiliation(s)
- Luis Werner
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Julika Hagn
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Udo Radius
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
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10
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van der Westhuizen D, Castro AC, Hazari N, Gevorgyan A. Bulky, electron-rich, renewable: analogues of Beller's phosphine for cross-couplings. Catal Sci Technol 2023; 13:6733-6742. [PMID: 38026730 PMCID: PMC10680433 DOI: 10.1039/d3cy01375h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 10/30/2023] [Indexed: 12/01/2023]
Abstract
In recent years, considerable progress has been made in the conversion of biomass into renewable chemicals, yet the range of value-added products that can be formed from biomass remains relatively small. Herein, we demonstrate that molecules available from biomass serve as viable starting materials for the synthesis of phosphine ligands, which can be used in homogeneous catalysis. Specifically, we prepared renewable analogues of Beller's ligand (di(1-adamantyl)-n-butylphosphine, cataCXium® A), which is widely used in homogeneous catalysis. Our new renewable phosphine ligands facilitate Pd-catalysed Suzuki-Miyaura, Stille, and Buchwald-Hartwig coupling reactions with high yields, and our catalytic results can be rationalized based on the stereoelectronic properties of the ligands. The new phosphine ligands generate catalytic systems that can be applied for the late-stage functionalization of commercial drugs.
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Affiliation(s)
| | - Abril C Castro
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo 0315 Oslo Norway
| | - Nilay Hazari
- Department of Chemistry, Yale University New Haven Connecticut 06520 USA
| | - Ashot Gevorgyan
- Department of Chemistry, UiT The Arctic University of Norway 9037 Tromsø Norway
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11
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Werner L, Hagn J, Walpuski J, Radius U. Aluminum(III) Cations [(NHC) ⋅ AlMes 2 ] + : Synthesis, Characterization, and Application in FLP-Chemistry. Angew Chem Int Ed Engl 2023:e202312111. [PMID: 37877231 DOI: 10.1002/anie.202312111] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 10/24/2023] [Accepted: 10/25/2023] [Indexed: 10/26/2023]
Abstract
The three-coordinate aluminum cations ligated by N-heterocyclic carbenes (NHCs) [(NHC) ⋅ AlMes2 ]+ [B(C6 F5 )4 ]- (NHC=IMeMe 4, IiPrMe 5, IiPr 6, Mes=2,4,6-trimethylphenyl) were prepared via hydride abstraction of the alanes (NHC) ⋅ AlHMes2 (NHC=IMeMe 1, IiPrMe 2, IiPr 3) using [Ph3 C]+ [B(C6 F5 )4 ]- in toluene as hydride acceptor. If this reaction was performed in diethyl ether, the corresponding four-coordinate aluminum etherate cations [(NHC) ⋅ AlMes2 (OEt2 )]+ [B(C6 F5 )4 ]- 7-9 (NHC=IMeMe 7, IiPrMe 8, IiPr 9) were isolated. According to a theoretical and experimental assessment of the Lewis-acidity of the [(IMeMe ) ⋅ AlMes2 ]+ cation is the acidity larger than that of B(C6 F5 )3 and of similar magnitude as reported for Al(C6 F5 )3 . The reaction of [(IMeMe ) ⋅ AlMes2 ]+ [B(C6 F5 )4 ]- 4 with the sterically less demanding, basic phosphine PMe3 afforded a mixed NHC/phosphine stabilized cation [(IMeMe ) ⋅ AlMes2 (PMe3 )]+ [B(C6 F5 )4 ]- 10. Equimolar mixtures of 4 and the sterically more demanding PCy3 gave a frustrated Lewis-pair (FLP), i.e., [(IMeMe ) ⋅ AlMes2 ]+ [B(C6 F5 )4 ]- /PCy3 FLP-11, which reacts with small molecules such as CO2 , ethene, and 2-butyne.
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Affiliation(s)
- Luis Werner
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Julika Hagn
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Janis Walpuski
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Udo Radius
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
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12
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Akram MO, Martin CD, Dutton JL. The Effect of Carborane Substituents on the Lewis Acidity of Boranes. Inorg Chem 2023; 62:13495-13504. [PMID: 37560972 DOI: 10.1021/acs.inorgchem.3c01872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
The Lewis acidity of primary, secondary, and tertiary boranes with phenyl, pentafluorophenyl, and all three isomers of the C-substituted icosahedral carboranes (ortho, meta, and para) was investigated by computing their fluoride, hydride, and ammonia affinities as well as their global electrophilicity indices and LUMO energies. From these calculations, it was determined that the substituent effects on the Lewis acidity of these boranes follow the trend of ortho-carborane > meta-carborane > para-carborane > C6F5 > C6H5.
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Affiliation(s)
- Manjur O Akram
- Baylor University, Department of Chemistry and Biochemistry, One Bear Place #97348, Waco, Texas 76798, United States
| | - Caleb D Martin
- Baylor University, Department of Chemistry and Biochemistry, One Bear Place #97348, Waco, Texas 76798, United States
| | - Jason L Dutton
- La Trobe University, Department of Chemistry, La Trobe Institute for Molecular Science, Melbourne, Victoria 3086,Australia
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13
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Akram MO, Tidwell JR, Dutton JL, Martin CD. Bis(1-Methyl-ortho-Carboranyl)Borane. Angew Chem Int Ed Engl 2023; 62:e202307040. [PMID: 37338991 DOI: 10.1002/anie.202307040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 06/22/2023]
Abstract
The Lewis superacid, bis(1-methyl-ortho-carboranyl)borane, is rapidly accessed in two steps. It is a very effective hydroboration reagent capable of B-H addition to alkenes, alkynes, and cyclopropanes. To date, this is the first identified Lewis superacidic secondary borane and most reactive neutral hydroboration reagent.
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Affiliation(s)
- Manjur O Akram
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - John R Tidwell
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Jason L Dutton
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Caleb D Martin
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
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14
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Vashisth K, Dutta S, Akram MO, Martin CD. Examining the reactivity of tris( ortho-carboranyl)borane with Lewis bases and application in frustrated Lewis pair Si-H bond cleavage. Dalton Trans 2023. [PMID: 37377440 DOI: 10.1039/d3dt01557b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Reactions of tris(ortho-carboranyl)borane with Lewis bases reveals only small bases bind. The tremendous bulk and Lewis acidity is leveraged in frustrated Lewis pair Si-H cleavage with a wider range of Lewis bases and greater efficacy than B(C6F5)3.
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Affiliation(s)
- Kanika Vashisth
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798, USA.
| | - Sanjay Dutta
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798, USA.
| | - Manjur O Akram
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798, USA.
| | - Caleb D Martin
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798, USA.
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