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He M, Hu C, Wei R, Wang XF, Liu LL. Recent advances in the chemistry of isolable carbene analogues with group 13-15 elements. Chem Soc Rev 2024; 53:3896-3951. [PMID: 38436383 DOI: 10.1039/d3cs00784g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
Carbenes (R2C:), compounds with a divalent carbon atom containing only six valence shell electrons, have evolved into a broader class with the replacement of the carbene carbon or the RC moiety with main group elements, leading to the creation of main group carbene analogues. These analogues, mirroring the electronic structure of carbenes (a lone pair of electrons and an empty orbital), demonstrate unique reactivity. Over the last three decades, this area has seen substantial advancements, paralleling the innovations in carbene chemistry. Recent studies have revealed a spectrum of unique carbene analogues, such as monocoordinate aluminylenes, nitrenes, and bismuthinidenes, notable for their extraordinary properties and diverse reactivity, offering promising applications in small molecule activation. This review delves into the isolable main group carbene analogues that are in the forefront from 2010 and beyond, spanning elements from group 13 (B, Al, Ga, In, and Tl), group 14 (Si, Ge, Sn, and Pb) and group 15 (N, P, As, Sb, and Bi). Specifically, this review focuses on the potential amphiphilic species that possess both lone pairs of electrons and vacant orbitals. We detail their comprehensive synthesis and stabilization strategies, outlining the reactivity arising from their distinct structural characteristics.
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Affiliation(s)
- Mian He
- Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Chaopeng Hu
- Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Rui Wei
- Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Xin-Feng Wang
- Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Liu Leo Liu
- Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
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2
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Liu S, Li Y, Lin J, Ke Z, Grützmacher H, Su CY, Li Z. Sequential radical and cationic reactivity at separated sites within one molecule in solution. Chem Sci 2024; 15:5376-5384. [PMID: 38577367 PMCID: PMC10988588 DOI: 10.1039/d4sc00201f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 02/29/2024] [Indexed: 04/06/2024] Open
Abstract
Distonic radical cations (DRCs) with spatially separated charge and radical sites are expected to show both radical and cationic reactivity at different sites within one molecule. However, such "dual" reactivity has rarely been observed in the condensed phase. Herein we report the isolation of crystalline 1λ2,3λ2-1-phosphonia-3-phosphinyl-cyclohex-4-enes 2a,b˙+, which can be considered delocalized DRCs and were completely characterized by crystallographic, spectroscopic, and computational methods. These DRCs contain a radical and cationic site with seven and six valence electrons, respectively, which are both stabilized via conjugation, yet remain spatially separated. They exhibit reactivity that differs from that of conventional radical cations (CRCs); specifically they show sequential radical and cationic reactivity at separated sites within one molecule in solution.
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Affiliation(s)
- Shihua Liu
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
| | - Yinwu Li
- School of Materials Science and Engineering, Sun Yat-Sen University 510006 Guangzhou China
| | - Jieli Lin
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
| | - Zhuofeng Ke
- School of Materials Science and Engineering, Sun Yat-Sen University 510006 Guangzhou China
| | - Hansjörg Grützmacher
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
- Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir-Prelog-Weg 1 Zürich 8093 Switzerland
| | - Cheng-Yong Su
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
| | - Zhongshu Li
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
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3
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Jana S, Elvers BJ, Pätsch S, Sarkar P, Krummenacher I, Nayak MK, Maiti A, Chrysochos N, Pati SK, Schulzke C, Braunschweig H, Yildiz CB, Jana A. Air and Moisture Stable para- and ortho-Quinodimethane Derivatives Derived from bis- N-Heterocyclic Olefins. Org Lett 2023; 25:1799-1804. [PMID: 36662600 DOI: 10.1021/acs.orglett.2c03993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Herein we report the development of a new methodology for the synthesis of various quinodimethane derivatives under two-electron oxidation of bis-N-heterocyclic olefins linked by different π-conjugated aromatic spacers. In case of para- and ortho-phenylene bridge, we obtained air and moisture stable diimidazolium para- and ortho-quinodimethane derivatives. Analogues of the para-phenylene spacer such as tetrafluoro-p-phenylene and p-anthracene also led to the corresponding air and moisture stable quinodimethane derivatives. This emphasizes the influence of imidazolium substituents which facilitate the air and moisture stability of the quinodimethane derivatives. Differences were observed for the electron transfer processes: two one-electron vs one two-electron redox transitions between bis-N-heterocyclic olefins and diimidazolium-quinodimethanes depending on the employed π-conjugated aromatic spacer. The formation of the π-conjugated radical-cations, transient redox intermediates between bis-N-heterocyclic olefins and diimidazolium-quinodimethanes, was addressed by an EPR investigation.
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Affiliation(s)
- Subhadip Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489 Greifswald, Germany
| | - Sebastian Pätsch
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489 Greifswald, Germany
| | - Pallavi Sarkar
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Swapan K Pati
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489 Greifswald, Germany
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Cem B Yildiz
- Department of Aromatic and Medicinal Plants, University of Aksaray, Aksaray 68100, Turkey
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
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4
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Moerman A, Sosa Carrizo ED, Théron B, Cattey H, Le Gendre P, Fleurat-Lessard P, Normand AT. Template Synthesis of NPN' Pincer-type Ligands at Titanium Using an Ambiphilic Phosphide Scaffold. Inorg Chem 2022; 61:7642-7653. [PMID: 35500277 DOI: 10.1021/acs.inorgchem.2c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ti-imido complex [TiCl(NtBu)(BIPP)] [1; BIPP = bis(iminophosphoranyl)phosphide ligand] reacts with terminal alkynes R-C≡CH (R = phenyl, isopropenyl, cyclopropyl, and 2-pyridyl) via P-P bond cleavage of the BIPP ligand. The resulting complexes [TiCl(NPN')(NPhPPh2)] (2a-d) contain a pincer-type NPN' phosphide ligand that incorporates the terminal alkyne and the imido ligand from complex 1. Complexes 2a-d feature two chiral centers (Ti and P) with interdependent absolute configurations; thus, they are formed stereoselectively. Complex 2a (R = phenyl) undergoes chloride abstraction with [Et3SiHSiEt3][B(C6F5)4], yielding [Ti(NPN')(NPhPPh2)][B(C6F5)4] (3). Complex 3 is a moderately active and stereoselective initiator for the ring-opening polymerization of rac-lactide. Complex 3 activates the C═O bond of 4-iodobenzaldehyde to give complex 4 as a single diastereomer despite the presence of three chiral centers. Complex 3 undergoes transmetallation with SbCl3, yielding [Sb(NPN')][B(C6F5)4] (5) and [TiCl3(NPhPPh2)] (6) selectively. The bonding situation in 3 and 5 was analyzed using Bader's atoms in molecules and the electron localization function, showing that the nitrogen atoms of the NPN' ligand are electronically similar, and that the metal-phosphide interaction is more polar in the case of titanium.
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Affiliation(s)
- Alex Moerman
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
| | - E Daiann Sosa Carrizo
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
| | - Benjamin Théron
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
| | - Hélène Cattey
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
| | - Pierre Le Gendre
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
| | - Paul Fleurat-Lessard
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
| | - Adrien T Normand
- Institut de Chimie Moléculaire de L'Université de Bourgogne (ICMUB), Université de Bourgogne, 9 Avenue Alain Savary, Dijon 21000, France
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5
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Fischer M, Roy MMD, Hüller S, Schmidtmann M, Beckhaus R. Reaction of a bis(pentafulvene)titanium complex with an N-heterocyclic olefin: C-H-activation leads to resonance between a titanium vinyl and titanium alkylidene complex. Dalton Trans 2022; 51:10690-10696. [PMID: 35166757 DOI: 10.1039/d2dt00014h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The N-heterocyclic olefin (NHO) ImMe4CH2 (2) (ImMe4CH2 = (MeCNMe)2CCH2) was employed for the synthesis of the titanium complex 3 derived from an NHO ligand precursor. By reacting 2 with the bis(π-η5:σ-η1-pentafulvene)titanium complex 1a, the terminal ylidic methylene unit of 2 is deprotonated by the quaternary exocyclic carbon atom of one pentafulvene ligand of 1a yielding the titanium complex 3 which bears an anionic NHO ligand (ImMe4CH-). 3 was characterized by NMR spectroscopy, single crystal X-ray diffraction and quantum chemical calculations. The latter highlight that 3 is best described as a titanium vinyl complex with significant contribution of the titanium alkylidene resonance structure.
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Affiliation(s)
- Malte Fischer
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK. .,Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg, Postfach 2503, D-26111 Oldenburg, Germany.
| | - Matthew M D Roy
- Department of Chemistry, Catalysis Research Center and Institute for Silicon Chemistry, Technische Universität München, Germany
| | - Sascha Hüller
- Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg, Postfach 2503, D-26111 Oldenburg, Germany.
| | - Marc Schmidtmann
- Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg, Postfach 2503, D-26111 Oldenburg, Germany.
| | - Rüdiger Beckhaus
- Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg, Postfach 2503, D-26111 Oldenburg, Germany.
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6
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Guthardt R, Mellin J, Bruhn C, Siemeling U. 1,1′‐Ferrocenylene‐Bridged Bis(N‐Heterocyclic Olefin) Derivatives. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Robin Guthardt
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
| | - Johanna Mellin
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
| | - Clemens Bruhn
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
| | - Ulrich Siemeling
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
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7
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Watson IC, Ferguson MJ, Rivard E. Zinc-Mediated Transmetalation as a Route to Anionic N-Heterocyclic Olefin Complexes in the p-Block. Inorg Chem 2021; 60:18347-18359. [PMID: 34738790 DOI: 10.1021/acs.inorgchem.1c02961] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Anionic N-heterocyclic olefins (aNHOs) are suited well for the stabilization of low-coordinate inorganic complexes, due to their steric tunability and strong σ- and π-electron donating abilities. In this study, the new two-coordinate zinc complex (MeIPrCH)2Zn (MeIPrCH = [(MeCNDipp)2C═CH]-, Dipp = 2,6-diisopropylphenyl) is shown to participate in a broad range of metathesis reactions with main group element-based halides and hydrides. In the case of the group 14 halides, Cl2E·dioxane (E = Ge and Sn), transmetalation occurs to form dinuclear propellane-shaped cations, [(MeIPrCHE)2(μ-Cl)]+, while the aNHO-capped phosphine ligand MeIPrCH-PPh2 is obtained when (MeIPrCH)2Zn is combined with ClPPh2. Lastly, ZnH2 elimination drives transmetalation between (MeIPrCH)2Zn and hydroboranes and hydroalumanes, leading to Lewis acidic aNHO-supported -boryl and -alane products.
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Affiliation(s)
- Ian C Watson
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada, T6G 2G2
| | - Michael J Ferguson
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada, T6G 2G2
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada, T6G 2G2
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8
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Ota K, Kinjo R. Heavier element-containing aromatics of [4 n+2]-electron systems. Chem Soc Rev 2021; 50:10594-10673. [PMID: 34369490 DOI: 10.1039/d0cs01354d] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
While the implication of the aromaticity concept has been dramatically expanded to date since its emergence in 1865, the classical [4n+2]/4n-electron counting protocol still plays an essential role in evaluating the aromatic nature of compounds. Over the last few decades, a variety of heavier heterocycles featuring the formal [4n+2] π-electron arrangements have been developed, which allows for assessing their aromatic nature. In this review, we present recent developments of the [4n+2]-electron systems of heavier heterocycles involving group 13-15 elements. The synthesis, spectroscopic data, structural parameters, computational data, and reactivity are introduced.
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Affiliation(s)
- Kei Ota
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Nanyang Link 21, Singapore 637371, Singapore
| | - Rei Kinjo
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Nanyang Link 21, Singapore 637371, Singapore
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9
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Gupta P, Siewert JE, Wellnitz T, Fischer M, Baumann W, Beweries T, Hering-Junghans C. Reactivity of phospha-Wittig reagents towards NHCs and NHOs. Dalton Trans 2021; 50:1838-1844. [PMID: 33471018 DOI: 10.1039/d1dt00071c] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Phospha-Wittig reagents, RPPMe3 (R = Mes* 2,4,6-tBu3-C6H2; MesTer 2,6-(2,4,6-Me3C6H2)-C6H3; DipTer 2,6-(2,6-iPr2C6H3)-C6H3), can be considered as phosphine-stabilized phosphinidenes. In this study we show that PMe3 can be displaced by NHCs or NHOs. Interestingly, phosphinidene-like reactivity results in a subsequent C(sp2)-H activation of the exocyclic CH2 group in NHOs. This concept was further extended to allyl-apended NHOs, which resulted in phosphine-substituted allyl species.
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Affiliation(s)
- Priyanka Gupta
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
| | - Jan-Erik Siewert
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
| | - Tim Wellnitz
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
| | - Malte Fischer
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
| | - Wolgang Baumann
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
| | - Torsten Beweries
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
| | - Christian Hering-Junghans
- Leibniz-Institut für Katalyse e.V. (LIKAT Rostock), Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
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10
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Watson IC, Zhou Y, Ferguson MJ, Kränzlein M, Rieger B, Rivard E. Trialkylaluminum N‐Heterocyclic Olefin (NHO) Adducts as Catalysts for the Polymerization of Michael‐Type Monomers. Z Anorg Allg Chem 2020. [DOI: 10.1002/zaac.201900331] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Ian C. Watson
- Department of Chemistry University of Alberta 11227 Saskatchewan Drive T6G 2G2 Edmonton Alberta Canada
| | - Yuqiao Zhou
- Department of Chemistry University of Alberta 11227 Saskatchewan Drive T6G 2G2 Edmonton Alberta Canada
| | - Michael J. Ferguson
- Department of Chemistry University of Alberta 11227 Saskatchewan Drive T6G 2G2 Edmonton Alberta Canada
| | - Moritz Kränzlein
- Catalysis Research Center & WACKER‐Chair of Macromolecular Chemistry Technical University of Munich Lichtenbergstrasse 4 85748 Garching Germany
| | - Bernhard Rieger
- Catalysis Research Center & WACKER‐Chair of Macromolecular Chemistry Technical University of Munich Lichtenbergstrasse 4 85748 Garching Germany
| | - Eric Rivard
- Department of Chemistry University of Alberta 11227 Saskatchewan Drive T6G 2G2 Edmonton Alberta Canada
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11
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Jayaraman A, Nilewar S, Jacob TV, Sterenberg BT. Sequential Electrophilic Substitution Reactions of Tungsten-Coordinated Phosphenium Ions and Phosphine Triflates. ACS OMEGA 2017; 2:7849-7861. [PMID: 31457342 PMCID: PMC6645012 DOI: 10.1021/acsomega.7b01424] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/01/2017] [Indexed: 06/10/2023]
Abstract
ion of chloride from [W(CO)5{PPhCl2}] with AgOSO2CF3 leads to the phosphine triflate complex [W(CO)5{PPhCl(OSO2CF3)}] which undergoes electrophilic substitution reactions with N,N-diethylaniline, anisole, N,N-dimethyl-p-toluidine, toluene, biphenyl, naphthalene, 2,7,9,9-tetramethyl xanthene, and allyltrimethylsilane to form the chlorophosphine complexes [W(CO)5{PPhClR}], where R = p-diethylanilinyl, p-anisyl, 2-(N,N-dimethyl-4-methylphenyl), p-tolyl, p-phenylphenyl, 1-naphthyl, 4-(2,7,9,9-tetramethylxanthyl), and allyl. Abstraction of the second chloride with AgOSO2CF3 leads, in most cases, to the respective phosphine triflates [W(CO)5{PPhR(OSO2CF3)}], which react with ferrocene to form the ferrocenyl phosphine complexes [W(CO)5{PPhR(C10H9Fe)}]. The W(CO)5 unit can be removed via photolysis in the presence of bis(diphenylphosphino)ethane to form metal-free phosphines.
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12
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Roy MMD, Rivard E. Pushing Chemical Boundaries with N-Heterocyclic Olefins (NHOs): From Catalysis to Main Group Element Chemistry. Acc Chem Res 2017; 50:2017-2025. [PMID: 28777537 DOI: 10.1021/acs.accounts.7b00264] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
N-Heterocyclic olefins (NHOs) have gone from the topic of a few scattered (but important) reports in the early 1990s to very recently being a ligand/reagent of choice in the far-reaching research fields of organocatalysis, olefin and heterocycle polymerization, and low oxidation state main group element chemistry. NHOs are formally derived by appending an alkylidene (CR2) unit onto an N-heterocyclic carbene (NHC), and their pronounced ylidic character leads to high nucleophilicity and soft Lewis basic character at the ligating carbon atom. These olefinic donors can also be structurally derived from imidazole, triazole, and thiazole-based heterocyclic carbenes and, as a result, have highly tunable electronic and steric properties. In this Account, we will focus on various synthetic routes to imidazole-2-ylidene derived NHOs (sometimes referred to as deoxy-Breslow intermediates) followed by a discussion of the electron-donor ability of this structurally tunable ligand group. It should be mentioned that NHOs have a close structural analogy with Breslow-type intermediates, N-heterocyclic ketene aminals, and β-azolium ylides; while these latter species play important roles in advancing synthetic organic chemistry, discussion in this Account will be confined mostly to imidazole-2-ylidene derived NHOs. In addition, we will cover selected examples from the literature where NHOs and their anionic counterparts, N-heterocyclic vinylenes, are used to access reactive main group species not attainable using traditional ligands. Added motivation for these studies comes from the emerging number of low coordinate main group element based compounds that display reactivity once reserved for precious metal complexes (such as H-H and C-H bond activation). Moreover, NHOs are versatile precursors to new mixed element (P/C and N/C), and potentially bidentate, ligand constructs of great potential in catalysis, where various metal oxidation states and coordination environments need to be stabilized during a catalytic cycle. The most active area of recent growth for NHOs is their use as nucleophiles to promote efficient organocatalytic transformations, including transesterification, carbonyl reduction, and the conversion of CO2 into value added products. Polyesters have also been generated through the NHO-promoted ring-opening polymerization of lactones, and the highly tunable nature of NHO organocatalysts allows for the rapid screening and enhancement of catalytic performance. Therefore, the growing utility of NHOs in the realm of organic and polymer chemistry can be viewed as evidence of the widespread impact of N-heterocyclic olefins on the chemical community. It is hoped that through this Account others will join this flourishing research domain and that the rapid recent growth of NHO chemistry is sustained for the foreseeable future.
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Affiliation(s)
- Matthew M. D. Roy
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta Canada, T6G 2G2
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta Canada, T6G 2G2
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13
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Affiliation(s)
- Philip P. Power
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Ching-Wen Chiu
- Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
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14
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Rottschäfer D, Neumann B, Stammler HG, Ghadwal RS. N
-Heterocyclic Vinylidene-Stabilized Phosphorus Biradicaloid. Chemistry 2017; 23:9044-9047. [DOI: 10.1002/chem.201702433] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Dennis Rottschäfer
- Universität Bielefeld; Fakultät für Chemie; Centrum für Molekulare Materialien; Anorganische Molekülchemie und Katalyse am Lehrstuhl für Anorganische Chemie und Strukturchemie; Universitätsstr. 25 33615 Bielefeld Germany
| | - Beate Neumann
- Universität Bielefeld; Fakultät für Chemie; Centrum für Molekulare Materialien; Anorganische Molekülchemie und Katalyse am Lehrstuhl für Anorganische Chemie und Strukturchemie; Universitätsstr. 25 33615 Bielefeld Germany
| | - Hans-Georg Stammler
- Universität Bielefeld; Fakultät für Chemie; Centrum für Molekulare Materialien; Anorganische Molekülchemie und Katalyse am Lehrstuhl für Anorganische Chemie und Strukturchemie; Universitätsstr. 25 33615 Bielefeld Germany
| | - Rajendra S. Ghadwal
- Universität Bielefeld; Fakultät für Chemie; Centrum für Molekulare Materialien; Anorganische Molekülchemie und Katalyse am Lehrstuhl für Anorganische Chemie und Strukturchemie; Universitätsstr. 25 33615 Bielefeld Germany
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