1
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Malhotra V, Elvers BJ, Dolai R, Chrysochos N, Bandaru SSM, Gangber T, Britto NJ, Krummenacher I, Rajaraman G, Braunschweig H, Schulzke C, Jana A. Cross-Coupling of NHC/CAAC-Based Carbodicarbene: Synthesis of Electron-Deficient Diradicaloids. J Am Chem Soc 2024. [PMID: 39425654 DOI: 10.1021/jacs.4c08876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2024]
Abstract
Herein, we report nickel(0)-catalyzed cross-coupling reactions of NHC/CAAC-based carbodicarbene (NHC = N-heterocyclic carbene and CAAC = cyclic(alkyl)(amino)carbene) with different aryl chlorides, bromides, and iodides. The resulting aryl-substituted cationic carbodicarbene derivatives are prone to one-electron oxidation yielding radical-dications, which, depending on the aryl motif employed, follow different modes of radical-radical dimerization and constitute an entry point to carbon/nitrogen- and nitrogen/nitrogen-centered diradicaloids. Subsequently, this coupling strategy was strategically applied to the synthesis of p-phenylene- and p,p'-biphenylene-bridged carbon/carbon-centered electron-deficient diradicaloids. The employed π-conjugated spacer plays a crucial role in determining the triplet population at room temperature by modulation of the singlet-triplet gap: EPR inactive for p-phenylene vs EPR active for p,p'-biphenylene. Nearly two decades after the disclosure of carbodicarbenes as donor-stabilized atomic carbon equivalents by Tonner and Frenking in 2007, we demonstrate their cross-couplings with a series of aryl halides/dihalides and, based on this, developed a modular methodology for the systematic synthesis of various electron-deficient diradicaloids.
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Affiliation(s)
- Vasu Malhotra
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, D-17489 Greifswald, Germany
| | - Ramapada Dolai
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | | | - Tejaswinee Gangber
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | | | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry and Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry and Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, D-17489 Greifswald, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
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2
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Wei R, Wang XF, Hu C, Liu LL. (Phosphino)(stannyl)carbene. Chem Commun (Camb) 2024; 60:9793-9796. [PMID: 39161315 DOI: 10.1039/d4cc03275f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
The synthesis of a (phosphino)(stannyl)carbene is documented. The combination of phosphino and stannyl substituents imparts a highly ambiphilic nature to this carbene, enabling reactions with cyanide, isocyanide, and carbon monoxide. This leads to rare stannylketenimines and a stannylketene.
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Affiliation(s)
- Rui Wei
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, China.
| | - Xin-Feng Wang
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, China.
| | - Chaopeng Hu
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, China.
| | - Liu Leo Liu
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, China.
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3
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Song Y, Zhu J. Spin population determines whether antiaromaticity can increase or decrease radical stability. Phys Chem Chem Phys 2024; 26:21213-21221. [PMID: 39073087 DOI: 10.1039/d4cp01031k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Aromaticity, as a classical and fundamental concept in chemistry, can enhance thermodynamic stability. In sharp contrast, a previous study showed that antiaromaticity rather than aromaticity can enhance the radical stability of α-methyl heterocyclic compounds. Here, we demonstrate a similar antiaromaticity-promoted radical stability when the methyl group is replaced by five-membered (alkyl)(amino)cyclics (AACs). More interestingly, when an AAC is fused with an antiaromatic ring, the radical stability could be either reduced or enhanced, depending on the spin population. Specifically, when the spin density is populated on an incoming antiaromatic 1,4-dihydro-1,4-diborinine moiety, the radical stability is enhanced whereas when the spin density is maintained on the original five-membered ring, the radical stability is reduced. Our findings highlight the importance of spin density in tuning the radical stability, inviting experimental chemists' verification.
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Affiliation(s)
- Yanlin Song
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
| | - Jun Zhu
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, People's Republic of China.
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4
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Madron du Vigné A, Cramer N. Streamlined synthetic assembly of α-chiral CAAC ligands and catalytic performance of their copper and ruthenium complexes. Chem Sci 2024:d4sc04278f. [PMID: 39129771 PMCID: PMC11306997 DOI: 10.1039/d4sc04278f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 07/23/2024] [Indexed: 08/13/2024] Open
Abstract
The unique electronic and steric parameters of chiral cyclic alkyl amino carbene (CAAC) ligands render them appealing steering ligands for enantioselective transition-metal catalyzed transformations. Due to the lack of efficient synthetic strategies to access particularly attractive α-chiral CAACs assessment and exploitation of their full synthetic potential remain difficult. Herein, we report a streamlined strategy to assemble a library of diastereo- and enantiomerically pure CAAC ligands featuring the notoriously difficult to access α-quaternary stereogenic centers. A tailored Julia-Kocienski olefination reagent allows the Claisen-rearrangement to be leveraged as an expedient route to form the synthetically pivotal racemic α-chiral methallyl aldehydes. Subsequent condensation with chiral amines and further cyclization provided a library of diastereomeric mixtures of the targeted ligand precursors. The CAAC salts as well as their corresponding metal complexes are conveniently separable by standard silica gel flash chromatography closing a long-standing accessibility gap in chiral CAAC ligands with proximal α-chirality. The rapid availability of both diastereomers enables testing of the relevance and synergistic effects of two chiral centers on the ligand in catalytic applications. A broad range of metal complexes with copper, gold, rhodium and ruthenium were obtained and structurally analyzed. The catalytic performances of the corresponding chiral CAAC copper and ruthenium complexes were assessed in enantioselective conjugate borylations and asymmetric ring closing metathesis, displaying selectivities of up 95 : 5 er.
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Affiliation(s)
- Adrien Madron du Vigné
- Laboratory of Asymmetric Catalysis and Synthesis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Nicolai Cramer
- Laboratory of Asymmetric Catalysis and Synthesis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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5
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Lachguar A, Del Rosal I, Maron L, Jeanneau E, Veyre L, Thieuleux C, Camp C. π-Bonding of Group 11 Metals to a Tantalum Alkylidyne Alkyl Complex Promotes Unusual Tautomerism to Bis-alkylidene and CO 2 to Ketenyl Transformation. J Am Chem Soc 2024; 146:18306-18319. [PMID: 38936814 PMCID: PMC11240581 DOI: 10.1021/jacs.4c02172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
A salt metathesis synthetic strategy is used to access rare tantalum/coinage metal (Cu, Ag, Au) heterobimetallic complexes. Specifically, complex [Li(THF)2][Ta(CtBu)(CH2tBu)3], 1, reacts with (IPr)MCl (M = Cu, Ag, Au, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) to afford the alkylidyne-bridged species [Ta(CH2tBu)3(μ-CtBu)M(IPr)] 2-M. Interestingly, π-bonding of group 11 metals to the Ta─C moiety promotes a rare alkylidyne alkyl to bis-alkylidene tautomerism, in which compounds 2-M are in equilibrium with [Ta(CHtBu)(CH2tBu)2(μ-CHtBu)M(IPr)] 3-M. This equilibrium was studied in detail using NMR spectroscopy and computational studies. This reveals that the equilibrium position is strongly dependent on the nature of the coinage metal going down the group 11 triad, thus offering a new valuable avenue for controlling this phenomenon. Furthermore, we show that these uncommon bimetallic couples could open attractive opportunities for synergistic reactivity. We notably report an uncommon deoxygenative carbyne transfer to CO2 resulting in rare examples of coinage metal ketenyl species, (tBuCCO)M(IPr), 4-M (M = Cu, Ag, Au). In the case of the Ta/Li analogue 1, the bis(alkylidene) tautomer is not detected, and the reaction with CO2 does not cleanly yield ketenyl species, which highlights the pivotal role played by the coinage metal partner in controlling these unconventional reactions.
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Affiliation(s)
- Abdelhak Lachguar
- Laboratory of Catalysis, Polymerization, Processes and Materials (CP2M UMR 5128), CNRS, Universite Claude Bernard Lyon 1, CPE-Lyon, Institut de Chimie de Lyon, 43 Bd du 11 Novembre 1918, Villeurbanne F-69616, France
| | - Iker Del Rosal
- CNRS, INSA, UPS, UMR 5215, LPCNO, Université de Toulouse, 135 Avenue de Rangueil, Toulouse F-31077, France
| | - Laurent Maron
- CNRS, INSA, UPS, UMR 5215, LPCNO, Université de Toulouse, 135 Avenue de Rangueil, Toulouse F-31077, France
| | - Erwann Jeanneau
- Centre de Diffractométrie Henri Longchambon, Université de Lyon, 5 Rue de la Doua, Villeurbanne 69100, France
| | - Laurent Veyre
- Laboratory of Catalysis, Polymerization, Processes and Materials (CP2M UMR 5128), CNRS, Universite Claude Bernard Lyon 1, CPE-Lyon, Institut de Chimie de Lyon, 43 Bd du 11 Novembre 1918, Villeurbanne F-69616, France
| | - Chloé Thieuleux
- Laboratory of Catalysis, Polymerization, Processes and Materials (CP2M UMR 5128), CNRS, Universite Claude Bernard Lyon 1, CPE-Lyon, Institut de Chimie de Lyon, 43 Bd du 11 Novembre 1918, Villeurbanne F-69616, France
| | - Clément Camp
- Laboratory of Catalysis, Polymerization, Processes and Materials (CP2M UMR 5128), CNRS, Universite Claude Bernard Lyon 1, CPE-Lyon, Institut de Chimie de Lyon, 43 Bd du 11 Novembre 1918, Villeurbanne F-69616, France
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6
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Karnamkkott HS, Das S, Mondal T, Mondal KC. Small molecule activation by sila/germa boryne species. J Comput Chem 2024; 45:804-819. [PMID: 38135467 DOI: 10.1002/jcc.27275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/19/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023]
Abstract
The inability of p-block elements to participate in π-backbonding restricts them from activating small molecules like CO, H2 , and so forth. However, the development of the main group metallomimetics became a new pathway, where the main-group elements like boron can bind and activate small molecules like CO and H2 . The concept of the frustrated Lewis pair, Boron-Boron multiple bonds, and borylene are previously illustrated. Some of these reported classes of boron species can mimic the jobs of the metal complexes. Hence, we have theoretically studied the binding of CO/N2 molecules at B-center of elusive species like sila/germa boryne stabilized by donor base ligands (cAAC)BE(Me)(L), where E Si, L cAACMe , NHCMe , PMe3 , E Ge, L cAACMe and (NHCMe )BE(Me)(cAACMe )). The substitutional analogues of (cAACR )BSiR1 (cAAC) and E P, L cAACMe ) have been studied by density functional theory (DFT), natural bond orbital, QTAIM calculations and energy decomposition analysis (EDA) coupled with natural orbital for chemical valence (NOCV) analyses. The computed bond dissociation energy and inner stability analyses by the EDA-NOCV method showed that the CO molecule can bind at the B-center of the above-mentioned species due to stronger σ-donor ability while binding of N2 has been theoretically predicted to be weak. The energy barrier for the CO binding is estimated to be 13-14 kcal/mol by transition state calculation. The change of partial triple bond character to single bond nature of the BSi bond and the bending of CBSi bond angle of sila-boryne species are the reason for the activation energy. Our study reveals the ability of such species to bind and activate the CO molecule to mimic the transition metal-containing complexes. We have additionally shown that binding of Fe(CO)4 and Ni(CO)3 is feasible at Si-center after binding of CO at the B-center.
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Affiliation(s)
| | - Sujit Das
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, India
| | - Totan Mondal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, India
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7
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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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8
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Merschel A, Vishnevskiy YV, Neumann B, Stammler HG, Ghadwal RS. Boosting the π-Acceptor Property of Mesoionic Carbenes by Carbonylation with Carbon Monoxide. Angew Chem Int Ed Engl 2024; 63:e202318525. [PMID: 38284508 DOI: 10.1002/anie.202318525] [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: 12/03/2023] [Revised: 01/17/2024] [Accepted: 01/17/2024] [Indexed: 01/30/2024]
Abstract
We report the room temperature dimerization of carbon monoxide mediated by C4/C5-vicinal anionic dicarbenes Li(ADC) (ADC = ArC{(Dipp)NC}2 ; Dipp = 2,6-iPr2 C6 H3 ; Ar = Ph, DMP (4-Me2 NC6 H4 ), Bp (4-PhC6 H4 )) to yield (E)-ethene-1,2-bis(olate) (i.e. - O-C=C-O- = COen ) bridged mesoionic carbene (iMIC) lithium compounds COen -[(iMIC)Li]2 (COen -[iMIC]2 = [ArC{(Dipp)NC}2 (CO)]2 ) in quantitative yields. COen -[(iMIC)Li]2 are highly colored stable solids, exhibit a strikingly small HOMO-LUMO energy gap, and readily undergo 2e-oxidations with selenium, CuCl (or CuCl2 ), and AgCl to afford the dinuclear compounds COon -[(iMIC)E]2 (E = Se, CuCl, AgCl) featuring a 1,2-dione bridged neutral bis-iMIC (i.e. COon -[iMIC]2 = [ArC{(Dipp)NC}2 (C=O)]2 ). COen -[(iMIC)Li]2 undergo redox-neutral salt metathesis reactions with LiAlH4 and (Et2 O)2 BeBr2 and afford COen -[(iMIC)AlH2 ]2 and COen -[(iMIC)BeBr]2 , in which the dianionic COen -moiety remains intact. All compounds have been characterized by NMR spectroscopy, mass spectrometry, and X-ray diffraction. Stereoelectronic properties of COon -[iMIC]2 are quantified by experimental and theoretical methods.
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Affiliation(s)
- Arne Merschel
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Yury V Vishnevskiy
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
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9
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Vermersch F, Wang VT, Abdellaoui M, Jazzar R, Bertrand G. Ambiphilicity of ring-expanded N-heterocyclic carbenes. Chem Sci 2024; 15:3707-3710. [PMID: 38455021 PMCID: PMC10915854 DOI: 10.1039/d3sc04543a] [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: 08/29/2023] [Accepted: 01/18/2024] [Indexed: 03/09/2024] Open
Abstract
N-heterocyclic carbenes, such as imidazole-2-ylidenes and imidazolin-2-ylidenes, the popular class of singlet carbenes introduced by Arduengo in 1991 have not been shown to be ambiphilic owing to the two σ-withdrawing, π-donating amino groups flanking the carbene centre. However, our experimental data suggest that ring-expanded N-heterocyclic carbenes (RE-NHCs), especially the seven and eight membered rings, are significantly ambiphilic. Our results also show that the steric environment in RE-NHCs can become a determining factor for controlling the E-H bond activation.
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Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093-0358 USA
| | - Victor T Wang
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093-0358 USA
| | - Mehdi Abdellaoui
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093-0358 USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093-0358 USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093-0358 USA
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10
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Wang Y, Tran PM, Lahm ME, Wei P, Adams ER, Schaefer HF, Robinson GH. From Carbene-Dithiolene Zwitterion Mediated B-H Bond Activation to BH 3·SMe 2-Assisted Boron-Boron Bond Formation. Organometallics 2023; 42:3328-3333. [PMID: 38098647 PMCID: PMC10716900 DOI: 10.1021/acs.organomet.3c00361] [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: 08/18/2023] [Indexed: 12/17/2023]
Abstract
The 1:1 reaction of the carbene-stabilized dithiolene zwitterion 1 with BH3·SMe2 gave the dithiolene-based hydroborane 2 and the doubly hydrogen-capped CAAC species 3 via hydride-coupled reverse electron transfer processes. The mechanism of this transformation was probed computationally using density functional theory. The subsequent 2:1 reaction of 2 with 1 resulted in 4 and 3, suggesting that 1 can mediate the B-H bond activation not only for BH3 but also for monohydroboranes. In the presence of BH3·SMe2, 2 was unexpectedly converted to the corresponding diborane(4) complex 5 through a dehydrocoupling reaction at an elevated temperature.
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Affiliation(s)
- Yuzhong Wang
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
| | - Phuong M. Tran
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
| | - Mitchell E. Lahm
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
| | - Pingrong Wei
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
| | - Earle R. Adams
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
| | - Henry F. Schaefer
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
| | - Gregory H. Robinson
- Department of Chemistry and
Center for Computational Chemistry, The
University of Georgia, Athens, Georgia 30602-2556, United States
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11
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Park J, Kim J, Jeong GY, Kim Y, Lee E. Uncovering Nitrosyl Reactivity at N-Heterocyclic Carbene Center. Angew Chem Int Ed Engl 2023:e202314978. [PMID: 37917039 DOI: 10.1002/anie.202314978] [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: 10/06/2023] [Revised: 10/31/2023] [Accepted: 11/02/2023] [Indexed: 11/03/2023]
Abstract
N-heterocyclic carbenes (NHCs) have garnered much attention due to their unique properties, such as strong σ-donating and π-accepting abilities, as well as their transition-metal-like reactivity toward small molecules. In 2015, we discovered that NHCs can react with nitric oxide (NO) gas to form radical adducts that resemble transition metal nitrosyl complexes. To elucidate the analogy between NHC and transition metal NO adducts, here we have undertaken a systematic investigation of the electron- and proton-transfer chemistry of [NHC-NO]⋅ (N-heterocyclic carbene nitric oxide radical) compounds. We have accessed a suite of compounds, comprised of [NHC-NO]+ , [NHC-NO]- , [NHC-NOH]0 , and [NHC-NHOH]+ species. In particular, [NHC-NO]- was isolated as potassium and lithium ion adducts. Most interestingly, a monomeric potassium [NHC-NO]- compound was isolated with the assistance of 18-crown-6, which is the first instance of a monomeric alkali N-oxyl compound to the best of our knowledge. Our results demonstrate that [NHC-NO]⋅ exhibits redox behavior broadly similar to metal nitrosyl complexes, which opens up more possibilities for utilizing NHCs to build on the known reactivity of metal complexes.
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Affiliation(s)
- Junbeom Park
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Jaelim Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Gu Yoon Jeong
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Youngsuk Kim
- Department of Chemistry, Pusan National University, Busan, 46241, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
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12
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Pei R, He L, Zhao Y, Wang X. The Dynamic Lewis Acid-Carbene Hybrid: Pushing the Electrophilicity of Carbenes to the Limit. J Am Chem Soc 2023; 145:21733-21737. [PMID: 37774109 DOI: 10.1021/jacs.3c07923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
This work describes a Lewis-acid-coordination strategy to efficiently enhance the electrophilicity of a carbene beyond structural modification. A hybrid BCF-DAC is formed by the coordination of a Lewis acid, B(C6F5)3 (BCF), to an N,N'-diamidocarbene (DAC), possessing superior low LUMO energy that is indicated by theoretical calculation. This endows the hybridized carbene with a unique reactivity that speeds up the activation of the sp3-hybridized C-H bond of toluene and the [2+1] cycloaddition with C2H2. More strikingly, the hybrid readily undergoes [2+1] cycloaddition with C2H4 under ambient conditions, which is the first example of a stable carbene reacting with ethylene. The Lewis acid approach also features dynamic behavior and electrophilicity tunability.
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Affiliation(s)
- Runbo Pei
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Liancheng He
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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13
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Krischer F, Jörges M, Leung TF, Darmandeh H, Gessner VH. Selectivity Control of the Ligand Exchange at Carbon in α-Metallated Ylides as a Route to Ketenyl Anions. Angew Chem Int Ed Engl 2023; 62:e202309629. [PMID: 37581571 DOI: 10.1002/anie.202309629] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/13/2023] [Accepted: 08/15/2023] [Indexed: 08/16/2023]
Abstract
α-Metallated ylides have recently been reported to undergo phosphine by CO exchange at the ylidic carbon atom to form isolable ketenyl anions. Systematic studies on the tosyl-substituted yldiides, R3 P=C(M)Ts (M=Li, Na, K), now reveal that carbonylation may lead to a competing metal salt (MTs) elimination. This side-reaction can be controlled by the choice of phosphine, metal cation, solvent and co-ligands, thus enabling the selective isolation of the ketenyl anion [Ts-CCO]M (2-M). Complexation of 2-Na by crown ether or cryptand allowed structure elucidation of the first free ketenyl anion [Ts-CCO]- , which showed an almost linear Ts-C-C linkage indicative for a pronounced ynolate character. However, DFT studies support a high charge at the ketenyl carbon atom, which is reflected in the selective carbon-centered reactivity. Overall, the present study provides important information on the selectivity control of ketenyl anion formation which will be crucial for future applications.
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Affiliation(s)
- Felix Krischer
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Mike Jörges
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Tsz-Fai Leung
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Heidar Darmandeh
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Viktoria H Gessner
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
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14
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Gruden E, Prinčič GG, Hočevar J, Iskra J, Kvíčala J, Tavčar G. From cyclic (alkyl)(amino)carbene (CAAC) precursors to fluorinating reagents. Experimental and theoretical study. Dalton Trans 2023. [PMID: 37368434 DOI: 10.1039/d3dt01476b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Addition of anhydrous HF to the hydrochloride [MeCAACH][Cl(HCl)0.5] resulted in the formation of salts with high HF content. By stepwise removal of HF in vacuo, we selectively prepared [MeCAACH][F(HF)2] (3) and [MeCAACH][F(HF)3] (4). We also characterised a salt with [F(HF)4]- anions within the structure of [MeCAACH][F(HF)3.5] (5). Compounds with a lower content of HF were not accessible under vacuum conditions. MeCAAC(H)F (1) was selectively prepared by abstraction of HF from 3 with CsF or KF, while [MeCAACH][F(HF)] (2) was prepared by mixing 3 and 1 in a 1 : 1 ratio. Compound 2 proved to be quite unstable as it tends to disproportionate into 1 and 3. This observation triggered our computational study, in which the structural relationships between CAAC-based fluoropyrrolidines and dihydropyrrolium fluorides were investigated using different DFT methods. The study showed that the results were very sensitive to the computational method used. For a correct description, the quality of the triple-ζ basis set was crucial. Surprisingly, the isodesmic reaction of [MeCAACH][F] + [MeCAACH][F(HF)2] → [MeCAACH][F(HF)] + [MeCAACH][F(HF)] did not confirm the low thermodynamic stability of 2. Furthermore, the use of 3 as a nucleophilic fluorinating reagent was tested on a range of organic substrates, as it is the most stable compound in this series. It was found to have the potential to fluorinate benzyl bromides, 1- and 2-alkyl bromides, silanes and sulfonyls with good to excellent yields of the target fluorides.
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Affiliation(s)
- Evelin Gruden
- Department of Inorganic Chemistry and Technology, "Jožef Stefan" Institute, Jamova cesta 39, Ljubljana, Slovenia.
| | - Griša Grigorij Prinčič
- Department of Chemistry and Biochemistry, University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Jan Hočevar
- Department of Chemistry and Biochemistry, University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Jernej Iskra
- Department of Chemistry and Biochemistry, University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Jaroslav Kvíčala
- Department of Organic Chemistry, University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Prague, Czech Republic
| | - Gašper Tavčar
- Department of Inorganic Chemistry and Technology, "Jožef Stefan" Institute, Jamova cesta 39, Ljubljana, Slovenia.
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15
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Koike T, Iwamoto T. Cyclobutenylidene: A Multifaceted Two-Coordinate Carbon Species Obtained via Skeletal Editing of a Cyclopropenylidene. J Am Chem Soc 2023; 145:9264-9272. [PMID: 37040540 DOI: 10.1021/jacs.3c01906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
C4H4 isomers not only serve as a basis to understand the chemical properties of hydrocarbons but are possible intermediates in combustion and organic reactions in outer space. Cyclobutenylidene (CBY), an elusive C4H4 isomer, is often proposed as a key intermediate in transition-metal-catalyzed metathesis and cycloaddition reactions between carbon-carbon multiple bonds. The geometrical structure of cyclobutenylidene predicted by calculations had been debated as whether it should be regarded as a carbocyclic carbene or a strained bridgehead alkene. Here, we report the synthesis of a crystalline cyclobutenylidene derivative, namely, a 3-silacyclobut-2-en-4-ylidene (SiCBY) via "carbene-to-carbene ring-expansion" reaction of an isolable diaminocyclopropenylidene induced by a silicon analogue of a carbene (silylene). The SiCBY exhibits multifaceted electronic properties which are corroborated by its extremely strong electron-donating properties and ambiphilic reactivity toward small gaseous molecules and C-H bonds. This result introduces an exciting strategy as well as a molecular motif to access low-valent carbon species with unusual electronic properties.
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Affiliation(s)
- Taichi Koike
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Takeaki Iwamoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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16
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Wang Y, Robinson GH. Counterintuitive Chemistry: Carbene Stabilization of Zero-Oxidation State Main Group Species. J Am Chem Soc 2023; 145:5592-5612. [PMID: 36876997 DOI: 10.1021/jacs.2c13574] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Carbenes have evolved from transient laboratory curiosities to a robust, diverse, and surprisingly impactful ligand class. A variety of different carbenes have significantly contributed to the development of low-oxidation state main group chemistry. This Perspective focuses upon advances in the chemistry of carbene complexes containing main group element cores in the formal oxidation state of zero, including their diverse synthetic strategies, unusual bonding and structural motifs, and utility in transition metal coordination chemistry and activation of small molecules.
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Affiliation(s)
- Yuzhong Wang
- Department of Chemistry, The University of Georgia, Athens, Georgia 30602-2556, United States
| | - Gregory H Robinson
- Department of Chemistry, The University of Georgia, Athens, Georgia 30602-2556, United States
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17
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Dolai R, Kumar R, Elvers BJ, Pal PK, Joseph B, Sikari R, Nayak MK, Maiti A, Singh T, Chrysochos N, Jayaraman A, Krummenacher I, Mondal J, Priyakumar UD, Braunschweig H, Yildiz CB, Schulzke C, Jana A. Carbodicarbenes and Striking Redox Transitions of their Conjugate Acids: Influence of NHC versus CAAC as Donor Substituents. Chemistry 2023; 29:e202202888. [PMID: 36129127 PMCID: PMC10100033 DOI: 10.1002/chem.202202888] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Indexed: 01/11/2023]
Abstract
Herein, a new type of carbodicarbene (CDC) comprising two different classes of carbenes is reported; NHC and CAAC as donor substituents and compare the molecular structure and coordination to Au(I)Cl to those of NHC-only and CAAC-only analogues. The conjugate acids of these three CDCs exhibit notable redox properties. Their reactions with [NO][SbF6 ] were investigated. The reduction of the conjugate acid of CAAC-only based CDC with KC8 results in the formation of hydrogen abstracted/eliminated products, which proceed through a neutral radical intermediate, detected by EPR spectroscopy. In contrast, the reduction of conjugate acids of NHC-only and NHC/CAAC based CDCs led to intermolecular reductive (reversible) carbon-carbon sigma bond formation. The resulting relatively elongated carbon-carbon sigma bonds were found to be readily oxidized. They were, thus, demonstrated to be potent reducing agents, underlining their potential utility as organic electron donors and n-dopants in organic semiconductor molecules.
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Affiliation(s)
- Ramapada Dolai
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Rahul Kumar
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Benedict J. Elvers
- Institut für BiochemieUniversität GreifswaldFelix-Hausdorff-Strasse 417489GreifswaldGermany
| | - Pradeep Kumar Pal
- International Institute of Information Technology GachibowliHyderabad500032India
| | - Benson Joseph
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Rina Sikari
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Tejender Singh
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - Arumugam Jayaraman
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Jagannath Mondal
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
| | - U. Deva Priyakumar
- International Institute of Information Technology GachibowliHyderabad500032India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Cem B. Yildiz
- Department of Aromatic and Medicinal PlantsAksaray UniversityAksaray68100Turkey
| | - Carola Schulzke
- Institut für BiochemieUniversität GreifswaldFelix-Hausdorff-Strasse 417489GreifswaldGermany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046TelanganaIndia
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18
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Arsenyeva KV, Piskunov AV. HETEROCYCLIC HEAVY ANALOGUES OF CARBENES: STRUCTURE AND CHEMICAL PROPERTIES. REVIEW. J STRUCT CHEM+ 2023. [DOI: 10.1134/s0022476623010018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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19
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Jörges M, Krischer F, Gessner VH. Transition metal-free ketene formation from carbon monoxide through isolable ketenyl anions. Science 2022; 378:1331-1336. [PMID: 36548404 DOI: 10.1126/science.ade4563] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The capacity of transition metals to bind and transform carbon monoxide (CO) is critical to its use in many chemical processes as a sustainable, inexpensive C1 building block. By contrast, only few s- and p-block element compounds bind and activate CO, and conversion of CO into useful carbonyl-containing organic compounds in such cases remains elusive. We report that metalated phosphorus ylides provide facile access to ketenyl anions ([RC=C=O]-) by phosphine displacement with CO. These anions are very stable and storable reagents with a distinctive electronic structure between that of the prototypical ketene (H2C=C=O) and that of ethynol (HC≡C-OH). Nonetheless, the ketenyl anions selectively react with a range of electrophiles at the carbon atom, thus offering high-yielding and versatile access to ketenes and related compounds.
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Affiliation(s)
- Mike Jörges
- Faculty of Chemistry and Biochemistry, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Felix Krischer
- Faculty of Chemistry and Biochemistry, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Viktoria H Gessner
- Faculty of Chemistry and Biochemistry, Ruhr-University Bochum, 44801 Bochum, Germany
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20
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Kim H, Lee E. Ambiphilic singlet carbenes: Electron donors and acceptors. B KOREAN CHEM SOC 2022. [DOI: 10.1002/bkcs.12620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hyunho Kim
- Department of Chemistry Pohang University of Science and Technology Pohang Republic of Korea
| | - Eunsung Lee
- Department of Chemistry Pohang University of Science and Technology Pohang Republic of Korea
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21
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Deoxygenating Reduction of CO 2 by [Cp*Al] 4 to Form a (Al 3O 2C) 2 Cluster Featuring Two Ketene Moieties. Inorg Chem 2022; 61:14500-14505. [PMID: 36053858 DOI: 10.1021/acs.inorgchem.2c01587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herein we report that the reaction of the low-valent aluminum(I) species [Cp*Al]4 (Cp* = pentamethylcyclopentadienyl) with CO2 exhibits complete cleavages of the C═O bonds. The deoxygenating reduction reaction of [Cp*Al]4 with CO2 at 120 °C afforded [(Cp*)3Al3O2C(CO)]2 (1), which featured two stacked (Al3O2C)2 units and two C═C═O ketene moieties. Moreover, the isoelectronic analogues of diimine and isothiocyanate with CO2 were also investigated, and the reactions of [Cp*Al]4 with Dipp*-N═C═N-Dipp* and Dipp-C═N═S [Dipp* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl; Dipp = 2,6-diisopropylphenyl] afforded dialuminylimine (2) and tetrameric [Cp*AlS]4 (3), respectively.
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22
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Volk J, Heinz M, Leibold M, Bruhn C, Bens T, Sarkar B, Holthausen MC, Siemeling U. A crystalline cyclic (alkyl)(amino)carbene with a 1,1'-ferrocenylene backbone. Chem Commun (Camb) 2022; 58:10396-10399. [PMID: 36039867 DOI: 10.1039/d2cc03871d] [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
Cyclic (alkyl)(amino)carbenes with a 1,1'-ferrocenylene backbone (fcCAACs) are established as an original family by the preparation of a crystalline congener. The Ccarbene bond angle is unprecedentedly wide for a CAAC, causing an exceptionally pronounced ambiphilicity. The redox-active backbone opens the door to unconventional metalloradicals and oligoradicals.
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Affiliation(s)
- Julia Volk
- Institut für Chemie, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany.
| | - Myron Heinz
- Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Straße 7, 60438 Frankfurt am Main, Germany
| | - Michael Leibold
- 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.
| | - Tobias Bens
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 50659 Stuttgart, Germany
| | - Biprajit Sarkar
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 50659 Stuttgart, Germany
| | - Max C Holthausen
- Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Straße 7, 60438 Frankfurt am Main, Germany
| | - Ulrich Siemeling
- Institut für Chemie, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany.
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23
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Serrato MR, Melaimi M, Bertrand G. Cyclic (amino)(barrelene)carbenes: an original family of CAACs through a novel synthetic pathway. Chem Commun (Camb) 2022; 58:7519-7521. [PMID: 35699417 DOI: 10.1039/d2cc02565e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A novel family of cyclic (alkyl)(amino)carbenes, which we name cyclic (amino)(barrelene)carbenes (CABCs) is reported. The key synthetic step involves an intramolecular [4+2] cyclization of an anthracene derivative with an alkyne. This synthetic approach allows for the attachment of both aryl and alkyl groups on the nitrogen atom. When used as ligand, two of the barrelene hydrogens are in close contact with the metal, which could stabilize low valent catalytic intermediates.
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Affiliation(s)
- Melinda R Serrato
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, 92093, USA.
| | - Mohand Melaimi
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, 92093, USA.
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, 92093, USA.
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24
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Maiti A, Elvers BJ, Bera S, Lindl F, Krummenacher I, Ghosh P, Braunschweig H, Yildiz CB, Schulzke C, Jana A. Disclosing Cyclic(Alkyl)(Amino)Carbenes as One-Electron Reductants: Synthesis of Acyclic(Amino)(Aryl)Carbene-Based Kekulé Diradicaloids. Chemistry 2022; 28:e202104567. [PMID: 35262232 PMCID: PMC9321839 DOI: 10.1002/chem.202104567] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Indexed: 11/10/2022]
Abstract
Herein, we disclose cyclic(alkyl)(amino)carbenes (CAACs) to be one-electron reductants under the formation of a transient radical cation as indicated by EPR spectroscopy. The disclosed CAAC reducing reactivity was used to synthesize acyclic(amino)(aryl)carbene-based Thiele and Chichibabin hydrocarbons, a new class of Kekulé diradicaloids. The results demonstrate CAACs to be potent organic reductants. Notably, the acyclic(amino)(aryl)carbene-based Chichibabin's hydrocarbon shows an appreciable population of the triplet state at room temperature, as evidenced by both variable-temperature NMR and EPR spectroscopy.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046, TelanganaIndia
| | - Benedict J. Elvers
- Institut für BiochemieUniversität GreifswaldFelix-Hausdorff-Straße 417489GreifswaldGermany
| | - Sachinath Bera
- Department of ChemistryRamakrishna Mission Residential College NarendrapurKolkata700103India
- Shahid Matangini Hazra Govt General Degree College for Women TamlukPurba Medinipur721649India
| | - Felix Lindl
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Prasanta Ghosh
- Department of ChemistryRamakrishna Mission Residential College NarendrapurKolkata700103India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Cem B. Yildiz
- Department of Aromatic and Medicinal PlantsAksaray UniversityAksaray68100Turkey
| | - Carola Schulzke
- Institut für BiochemieUniversität GreifswaldFelix-Hausdorff-Straße 417489GreifswaldGermany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046, TelanganaIndia
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25
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Liu TT, Zhai DD, Guan BT, Shi ZJ. Nitrogen fixation and transformation with main group elements. Chem Soc Rev 2022; 51:3846-3861. [PMID: 35481498 DOI: 10.1039/d2cs00041e] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nitrogen fixation is essential for the maintenance of life and development of society, however, the large bond dissociation energy and nonpolarity of the triple bond constitute a considerable challenge. The transition metals, by virtue of their combination of empty and occupied d orbitals, are prevalent in the nitrogen fixation studies and are continuing to receive a significant focus. The main group metals have always been considered incapable in dinitrogen activation owing to the absence of energetically and symmetrically accessible orbitals. The past decades have witnessed significant breakthroughs in the dinitrogen activation with the main group elements and compounds via either matrix isolation, theoretical calculations or synthetic chemistry. The successful reactions of the low-valent species of the main group elements with inert dinitrogen have been reported via the π back-donation from either the d orbitals (Ca, Sr, Ba) or p orbitals (Be, B, C…). Herein, the significant achievements have been briefly summarized, along with predicting the future developments.
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Affiliation(s)
- Tong-Tong Liu
- Department of Chemistry, Fudan University, 2005 Songhu Rd, Shanghai, 200438, China.
| | - Dan-Dan Zhai
- Department of Chemistry, Fudan University, 2005 Songhu Rd, Shanghai, 200438, China.
| | - Bing-Tao Guan
- Department of Chemistry, Fudan University, 2005 Songhu Rd, Shanghai, 200438, China.
| | - Zhang-Jie Shi
- Department of Chemistry, Fudan University, 2005 Songhu Rd, Shanghai, 200438, China.
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26
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Kumar Kushvaha S, Mishra A, Roesky HW, Chandra Mondal K. Recent Advances in the Domain of Cyclic (Alkyl)(Amino) Carbenes. Chem Asian J 2022; 17:e202101301. [PMID: 34989475 PMCID: PMC9307053 DOI: 10.1002/asia.202101301] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/25/2021] [Indexed: 12/03/2022]
Abstract
Isolation of cyclic (alkyl) amino carbenes (cAACs) in 2005 has been a major achievement in the field of stable carbenes due to their better electronic properties. cAACs and bicyclic(alkyl)(amino)carbene (BicAAC) in essence are the most electrophilic as well as nucleophilic carbenes are known till date. Due to their excellent electronic properties in terms of nucleophilic and electrophilic character, cAACs have been utilized in different areas of chemistry, including stabilization of low valent main group and transition metal species, activation of small molecules, and catalysis. The applications of cAACs in catalysis have opened up new avenues of research in the field of cAAC chemistry. This review summarizes the major results of cAAC chemistry published until August 2021.
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Affiliation(s)
| | - Ankush Mishra
- Department of ChemistryIndian Institute of Technology MadrasChennai600036India
| | - Herbert W. Roesky
- Institute of Inorganic ChemistryTammannstrasse 4D-37077GöttingenGermany
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27
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Affiliation(s)
- Shiori Fujimori
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
| | - Shigeyoshi Inoue
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
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28
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Cyclic (alkyl)(amino)carbene (CAAC) ligands: Electronic structure and application as chemically- and redox-non-innocent ligands and chromophores. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2022. [DOI: 10.1016/bs.adomc.2022.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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29
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Schoening J, Ganesamoorthy C, Wölper C, Solel E, Schreiner PR, Schulz S. Synthesis, electronic nature, and reactivity of selected silylene carbonyl complexes. Dalton Trans 2022; 51:8249-8257. [DOI: 10.1039/d2dt01335e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Room-temperature stable main group element carbonyl complexes are rare. Here we report on the synthesis of two such complexes, namely gallium-substituted silylene-carbonyl complexes [L(X)Ga]2SiCO (X = I 2, Me 3;...
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30
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Cai HX, Su DM, Bacha RUS, Pan QJ. CO 2 Cleavage Reaction Driven by Alkylidyne Complexes of Group 6 Metals and Uranium: A Density Functional Theory Study on Energetics, Reaction Mechanism, and Structural/Bonding Properties. Inorg Chem 2021; 60:18859-18869. [PMID: 34883015 DOI: 10.1021/acs.inorgchem.1c02654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Designing novel catalysts is essential for the efficient conversion of metal alkylidyne into metal oxo ketene complexes in the presence of CO2, which to some extent resolves the environmental concerns of the ever-increasing carbon emission. In this regard, a series of metal alkylidyne complexes, [b-ONO]M≡CCH3(THF)2 ([b-ONO] = {(C6H4[C(CF3)2O])2N}3-; M = Cr, Mo, W, and U), have been comprehensively studied by relativistic density functional theory calculations. The calculated thermodynamics and kinetics unravel that the tungsten complex is capable of catalyzing the CO2 cleavage reaction, agreeing with the experimental findings for its analogue. Interestingly, the uranium complex shows superior catalytic performance because of the associated considerably lower energy barrier and larger reaction rate constant. The M≡C moiety in the complexes turns out to be the active site for the [2 + 2] cyclic addition. In contrast, complexes of Cr and Mo could not offer good catalytic performance. Along the reaction coordinate, the M-C (M = Cr, Mo, W, and U) bond regularly transforms from triple to double to single bonds; concomitantly, the newly formed M-O in the product is identified to have a triple-bond character. The catalytic reactions have been extensively explained and addressed by geometric/electronic structures and bonding analyses.
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Affiliation(s)
- Hong-Xue Cai
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
| | - Dong-Mei Su
- State-Owned Assets Management Division, Harbin University, Harbin 150086, China
| | - Raza Ullah Shah Bacha
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
| | - Qing-Jiang Pan
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
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31
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Antoni PW, Reitz J, Hansmann MM. N 2/CO Exchange at a Vinylidene Carbon Center: Stable Alkylidene Ketenes and Alkylidene Thioketenes from 1,2,3-Triazole Derived Diazoalkenes. J Am Chem Soc 2021; 143:12878-12885. [PMID: 34348463 DOI: 10.1021/jacs.1c06906] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We present a new class of room-temperature stable diazoalkenes featuring a 1,2,3-triazole backbone. Dinitrogen of the diazoalkene moiety can be thermally displaced by an isocyanide and carbon monoxide. The latter alkylidene ketenes are typically considered as highly reactive compounds, traditionally only accessible by flash vacuum pyrolysis. We present a new and mild synthetic approach to the first structurally characterized alkylidene ketenes by a substitution reaction. Density functional theory calculations suggest the substitution with isocyanides to take place via a stepwise addition/elimination mechanism. In the case of carbon monoxide, the reaction proceeds through an unusual concerted exchange at a vinylidene carbon center. The vinylidene ketenes react with carbon disulfide via a four-membered thiete intermediate to give vinylidene thioketenes under release of COS. We present spectroscopic as well as structural data for the complete isoelectronic series (R2C═C═X; X = N2, CO, CNR, CS) including 1J(13C-13C) data. As N2, CO, and isocyanides belong to the archetypical ligands in transition-metal chemistry, this process can be interpreted in analogy to coordination chemistry as a ligand exchange reaction at a vinylidene carbon center.
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Affiliation(s)
- Patrick W Antoni
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany
| | - Justus Reitz
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany
| | - Max M Hansmann
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany
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32
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Abstract
Although silylene-carbonyl complexes are known for decades, only recently isolable examples have been accomplished. In this work, the bonding situation is re-evaluated to explain the origins of their remarkable stability within the Kohn-Sham molecular orbital theory framework. It is shown that the chemical bond can be understood as CO interaction with the silylene via a donor-acceptor interaction: a σ-donation from the σCO into the empty p-orbital of silicon, and a π-back donation from the sp2 lone pair of silicon into the π*CO antibonding orbitals. Notably, it was established that the driving force behind the surprisingly stable Si-CO compounds, however, is another π-back donation from a perpendicular bonding R-Si σ-orbital into the π*CO antibonding orbitals. Consequently, the pyramidalization of the central silicon atom cannot be associated with the strength of the π-back donation, in sharp contrast to the established chemical bonding model. Considering this additional bonding interaction not only shed light on the bonding situation, but is also an indispensable key for broadening the scope of silylene-carbonyl chemistry.
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Affiliation(s)
- Tetiana Sergeieva
- Inorganic and Computational Chemistry GroupChemistry DepartmentSaarland UniversityCampus C4.166123SaarbrückenGermany
| | - Debdeep Mandal
- Inorganic and Computational Chemistry GroupChemistry DepartmentSaarland UniversityCampus C4.166123SaarbrückenGermany
| | - Diego M. Andrada
- Inorganic and Computational Chemistry GroupChemistry DepartmentSaarland UniversityCampus C4.166123SaarbrückenGermany
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33
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Zhou L, Zhang D, Hu J, Wu Y, Geng J, Hu X. Thermal Dehydrogenation and Hydrolysis of BH3NH3 Catalyzed by Cyclic (Alkyl)(amino)carbene Iridium Complexes under Mild Conditions. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00302] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lei Zhou
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Dejin Zhang
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Jinling Hu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Youting Wu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Jiao Geng
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Xingbang Hu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
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34
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Zheng X, Zulkifly I, Heilmann A, McManus C, Aldridge S. Colorimetric Metal-Free Detection of Carbon Monoxide: Reversible CO Uptake by a BNB Frustrated Lewis Pair. Angew Chem Int Ed Engl 2021; 60:16416-16419. [PMID: 34047424 PMCID: PMC8362209 DOI: 10.1002/anie.202106413] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Indexed: 01/03/2023]
Abstract
We report two BNB‐type frustrated Lewis pairs which feature an acceptor‐donor‐acceptor functionalized cavity, and which differ in the nature of the B‐bound fluoroaryl group (C6F5 vs. C6H3(CF3)2‐3,5, Arf). These receptor systems are capable of capturing gaseous CO, and in the case of the ‐BArf2 system this can be shown to occur in reversible fashion at/above room temperature. For both systems, the binding event is accompanied by migration of one of the aryl substituents to the electrophilic carbon of the CO guest. Experiments utilizing an additional equivalent of PtBu3 allow the initially formed (non‐migrated) CO adduct to be identified and trapped (via demethylation), while also establishing the reversibility of the B‐to‐C migration process. When partnered with the slightly less Lewis acidic ‐BArf2 substituent, this reversibility allows for release of the captured carbon monoxide in the temperature range 40–70 °C, and the possibility for CO sensing, making use of the associated colourless to orange/red colour change.
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Affiliation(s)
- Xiongfei Zheng
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Ili Zulkifly
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Andreas Heilmann
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Caitilín McManus
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Simon Aldridge
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
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35
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Zheng X, Zulkifly I, Heilmann A, McManus C, Aldridge S. Colorimetric Metal‐Free Detection of Carbon Monoxide: Reversible CO Uptake by a BNB Frustrated Lewis Pair. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiongfei Zheng
- Inorganic Chemistry Laboratory Department of Chemistry University of Oxford South Parks Road Oxford OX1 3QR UK
| | - Ili Zulkifly
- Inorganic Chemistry Laboratory Department of Chemistry University of Oxford South Parks Road Oxford OX1 3QR UK
| | - Andreas Heilmann
- Inorganic Chemistry Laboratory Department of Chemistry University of Oxford South Parks Road Oxford OX1 3QR UK
| | - Caitilín McManus
- Inorganic Chemistry Laboratory Department of Chemistry University of Oxford South Parks Road Oxford OX1 3QR UK
| | - Simon Aldridge
- Inorganic Chemistry Laboratory Department of Chemistry University of Oxford South Parks Road Oxford OX1 3QR UK
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36
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Rajendran NM, Gautam N, Sarkar P, Ahmed J, Das A, Das S, Pati SK, Mandal SK. Bicyclic (alkyl)(amino)carbene stabilized zinc(0) complex with singlet biradicaloid ground state. Chem Commun (Camb) 2021; 57:5282-5285. [PMID: 33942839 DOI: 10.1039/d1cc01298c] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A storable bicyclic (alkyl)(amino)carbene (BICAAC) stabilized two coordinate zinc(0) complex [(BICAAC)2Zn] (2) was synthesized. DFT calculations reveal that BICAAC plays a decisive role in imparting the stability to 2. This complex activates the C(sp3)-Cl bond of trityl chloride generating the Gomberg's free radical with greater efficiency than metallic Zn powder.
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Affiliation(s)
- N M Rajendran
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India.
| | - Nimisha Gautam
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India.
| | - Pallavi Sarkar
- Theoretical Sciences Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore 560064, India.
| | - Jasimuddin Ahmed
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India.
| | - Arpan Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India.
| | - Shubhajit Das
- Theoretical Sciences Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore 560064, India.
| | - Swapan K Pati
- Theoretical Sciences Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Bangalore 560064, India.
| | - Swadhin K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India.
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37
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Chakrabortty S, Kaur M, Adhikari M, Manar KK, Singh S. A Bis (BICAAC) Palladium(II) Complex: Synthesis and Implementation as Catalyst in Heck-Mizoroki and Suzuki-Miyaura Cross Coupling Reactions. Inorg Chem 2021; 60:6209-6217. [PMID: 33844912 DOI: 10.1021/acs.inorgchem.0c03614] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbenes are one of the most appealing, well-explored, and exciting ligands in modern chemistry due to their tunable stereoelectronic properties and a wide area of applications. A palladium complex (BICAAC)2PdCl2 with a recently discovered cyclic (alkyl)(amino)carbene having bicyclo[2.2.2] octane skeleton (BICAAC) was synthesized and characterized. The enhanced σ-donating and π-accepting ability of this carbene lend a hand to form a robust Pd-carbene bond, which allowed us to probe its reactivity as a precatalyst in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions with low catalyst loading in open-air conditions. The diverse range of substrates was explored for both the cross-coupling reactions. To get a better understanding of the catalytic reactions, several analytical techniques such as field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and powder X-ray diffraction were employed in a conclusive manner.
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Affiliation(s)
- Soumyadeep Chakrabortty
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, Punjab, India
| | - Mandeep Kaur
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, Punjab, India
| | - Manu Adhikari
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, Punjab, India
| | - Krishna K Manar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, Punjab, India
| | - Sanjay Singh
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, Punjab, India
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38
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Termühlen S, Blumenberg J, Hepp A, Daniliuc CG, Hahn FE. Preparation of Complexes Bearing N‐Alkylated, Anionic or Protic CAACs Through Oxidative Addition of 2‐Halogenoindole Derivatives. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202010988] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sebastian Termühlen
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstrasse 30 48149 Münster Germany
| | - Jonas Blumenberg
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstrasse 30 48149 Münster Germany
| | - Alexander Hepp
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstrasse 30 48149 Münster Germany
| | - Constantin G. Daniliuc
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstrasse 40 48149 Münster Germany
| | - F. Ekkehardt Hahn
- Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Corrensstrasse 30 48149 Münster Germany
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39
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Termühlen S, Blumenberg J, Hepp A, Daniliuc CG, Hahn FE. Preparation of Complexes Bearing N-Alkylated, Anionic or Protic CAACs Through Oxidative Addition of 2-Halogenoindole Derivatives. Angew Chem Int Ed Engl 2021; 60:2599-2602. [PMID: 33022849 PMCID: PMC7898591 DOI: 10.1002/anie.202010988] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Indexed: 11/09/2022]
Abstract
CAAC precursors 2-chloro-3,3-dimethylindole 1 and 2-chloro-1-ethyl-3,3-dimethylindolium tetrafluoroborate 2BF4 have been prepared and oxidatively added to [M(PPh3 )4 ] (M=Pd, Pt). Salt 2BF4 reacts with [Pd(PPh3 )4 ] in toluene at 25 °C over 4 days to yield complex cis-[3]BF4 featuring an N-ethyl substituted CAAC, two cis-arranged phosphines and a chloro ligand. Compound trans-[3]BF4 was obtained from the same reaction at 80 °C over 1 day. Salt 2BF4 reacts with [Pt(PPh3 )4 ] to give cis-[4]BF4 . The neutral indole derivative 1 adds oxidatively to [Pt(PPh3 )4 ] to give trans-[5] featuring a CAAC ligand with an unsubstituted ring-nitrogen atom. This nitrogen atom has been protonated with py⋅HBF4 to give trans-[6]BF4 bearing a protic CAAC ligand. The PdII complex trans-[7]BF4 bearing a protic CAAC ligand was obtained in a one-pot reaction from 1 and [Pd(PPh3 )4 ] in the presence of py⋅HBF4 .
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Affiliation(s)
- Sebastian Termühlen
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149, Münster, Germany
| | - Jonas Blumenberg
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149, Münster, Germany
| | - Alexander Hepp
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149, Münster, Germany
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
| | - F Ekkehardt Hahn
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149, Münster, Germany
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40
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Morvan J, Mauduit M, Bertrand G, Jazzar R. Cyclic (Alkyl)(amino)carbenes (CAACs) in Ruthenium Olefin Metathesis. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05508] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jennifer Morvan
- Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR UMR 6226, F-35000 Rennes, France
| | - Marc Mauduit
- Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR UMR 6226, F-35000 Rennes, France
| | - Guy Bertrand
- UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358, United States
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358, United States
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41
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Jakhar V, Pal D, Ghiviriga I, Abboud KA, Lester DW, Sumerlin BS, Veige AS. Tethered Tungsten-Alkylidenes for the Synthesis of Cyclic Polynorbornene via Ring Expansion Metathesis: Unprecedented Stereoselectivity and Trapping of Key Catalytic Intermediates. J Am Chem Soc 2021; 143:1235-1246. [PMID: 33417768 DOI: 10.1021/jacs.0c12248] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This report describes an approach for preparing tethered tungsten-imido alkylidene complexes featuring a tetra-anionic pincer ligand. Treating the tungsten alkylidyne [tBuOCO]W≡CtBu(THF)2 (1) with isocyanates (RNCO; R = tBu, Cy, and Ph) leads to cycloaddition occurring exclusively at the C═N bond to generate the tethered tungsten-imido alkylidenes (6-NR). Unanticipated intermediates reveal themselves, including the discovery of [(O2CtBuC═)W(η2-(N,C)-RNCO)(THF)] (11-R) and an unprecedented decarbonylation product [(tBuOCO)W(≡NR)(tBuCCO)] (14-R), on the pathway to the formation of 6-NR. Complex 11-R is kinetically stable for sterically bulky isocyanate R = tBu (11-tBu) and is isolated and characterized by single-crystal X-ray diffraction. Finally, adding to the short list of catalysts capable of ring expansion metathesis polymerization (REMP), complexes 6-NR and 11-tBu are active for the stereoselective synthesis of cyclic polynorbornene.
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Affiliation(s)
- Vineet Jakhar
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Digvijayee Pal
- George and Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science and Engineering, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Ion Ghiviriga
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Khalil A Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Daniel W Lester
- Polymer Characterization Research Technology Platform, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Brent S Sumerlin
- George and Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science and Engineering, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Adam S Veige
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
- George and Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science and Engineering, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
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42
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Proetto MT, Alexander K, Melaimi M, Bertrand G, Gianneschi NC. Cyclic (Alkyl)(Amino)Carbene (CAAC) Gold(I) Complexes as Chemotherapeutic Agents. Chemistry 2021; 27:3772-3778. [PMID: 33090571 DOI: 10.1002/chem.202004317] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Indexed: 12/31/2022]
Abstract
Cyclic (Alkyl)(Amino)Carbenes (CAACs) have become forceful ligands for gold due to their ability to form very strong ligand-metal bonds. Inspired by the success of Auranofin and other gold complexes as antitumor agents, we have studied the cytotoxicity of bis- and mono-CAAC-gold complexes on different cancer cell lines: HeLa (cervical cancer), A549 (lung cancer), HT1080 (fibrosarcoma) and Caov-3 (ovarian cancer). Further investigations aimed at elucidating their mechanism of action are described. This includes quantification of affinities for TrxR, evaluation of their bioavailability and determination of associated cell death process. Moreover, Transmission Electron Microscopy (TEM) was used to study morphological changes upon exposure. Noticeably, a significant reduction in non-specific binding to serum proteins was observed with CAAC complexes when compared to Auranofin. These results confirm the potential of CAAC-gold complexes in biological environments, which may result in more specific drug-target interactions and decreased side effects.
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Affiliation(s)
- Maria T Proetto
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.,Department of Chemistry, Department of Materials Science & Engineering, Department of Biomedical Engineering and Department of Pharmacology, International Institute for Nanotechnology, Simpson Querrey Institute, Chemistry of Life Processes Institute and Lurie Cancer Center, Northwestern University, Evanston, Il, 60208, USA
| | - Kelsey Alexander
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Mohand Melaimi
- UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Nathan C Gianneschi
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.,Department of Chemistry, Department of Materials Science & Engineering, Department of Biomedical Engineering and Department of Pharmacology, International Institute for Nanotechnology, Simpson Querrey Institute, Chemistry of Life Processes Institute and Lurie Cancer Center, Northwestern University, Evanston, Il, 60208, USA
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43
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Koike T, Kosai T, Iwamoto T. Intermolecular C-H Activation at the Allylic/Benzylic and Homoallylic/Homobenzylic Positions of Cyclic Hydrocarbons by a Stable Divalent Silicon Species. Chemistry 2021; 27:724-734. [PMID: 32931054 DOI: 10.1002/chem.202003541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/26/2020] [Indexed: 11/11/2022]
Abstract
Direct activation of inert C(sp3 )-H bonds by main group element species is yet a formidable challenge. Herein, the dehydrogenation of cyclohexene and 1,2,3,4-tetrahydronaphthalene through the allylic/benzylic and homoallylic/homobenzylic C-H bond activation by cyclic (alkyl)(amino)silylene 1 in neat conditions is reported to yield the corresponding aromatic compounds. As for the reaction of cyclohexene, allylsilane 3 and 7-silanorbornene 4 were also observed, which could be interpreted as a direct dehydrogenative silylation reaction of monoalkenes at the allylic positions. Experimental and computational studies suggest that the dehydrogenation of cyclohexene at the homoallylic position was accomplished by a combination of silylene 1 and radical intermediates such as hydrosilyl radical INT1 or cyclohexenyl radical H, which are generated in the initial step of the reaction.
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Affiliation(s)
- Taichi Koike
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
| | - Tomoyuki Kosai
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
| | - Takeaki Iwamoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
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Fujimori S, Inoue S. Main group carbonyl complexes. Commun Chem 2020; 3:175. [PMID: 36703371 PMCID: PMC9814907 DOI: 10.1038/s42004-020-00423-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 10/26/2020] [Indexed: 01/29/2023] Open
Affiliation(s)
- Shiori Fujimori
- grid.6936.a0000000123222966Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
| | - Shigeyoshi Inoue
- grid.6936.a0000000123222966Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany
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45
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Ghosh B, Bharadwaz P, Sarkar N, Phukan AK. Activation of small molecules by cyclic alkyl amino silylenes (CAASis) and germylenes (CAAGes): a theoretical study. Dalton Trans 2020; 49:13760-13772. [PMID: 32996965 DOI: 10.1039/d0dt03043k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Quantum chemical calculations have been carried out on a series of skeletally modified cyclic alkyl amino silylenes (CAASis) and germylenes (CAAGes) to understand their ligand properties and reactivity towards the activation of a variety of small molecules. The installation of boron or silicon atoms into the ring framework of these silylenes/germylenes led to a dramatic increase in their σ-basicity while the incorporation of ylidic moieties resulted in a sharp reduction of their π-acidity although it did help in increasing the electron donation ability. The calculated values of energy barriers for the activation of H-H, N-H, C-H and Si-H bonds by many of the cyclic silylenes considered here are found to be comparable to those for experimentally evaluated systems, indicating the potential of these computationally designed molecules in small molecule activation and calling for synthetic efforts towards their isolation. Furthermore, activations employing CAAGes are found to be more demanding than those with CAASis which may be attributed to the significantly lower Lewis basicity of the former than the latter.
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Affiliation(s)
- Bijoy Ghosh
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India.
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46
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Reiter D, Holzner R, Porzelt A, Frisch P, Inoue S. Silylated silicon-carbonyl complexes as mimics of ubiquitous transition-metal carbonyls. Nat Chem 2020; 12:1131-1135. [PMID: 33071286 DOI: 10.1038/s41557-020-00555-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 08/20/2020] [Indexed: 11/09/2022]
Abstract
Transition-metal-carbonyl complexes are common organometallic reagents that feature metal-CO bonds. These complexes have proven to be powerful catalysts for various applications. By contrast, silicon-carbonyl complexes, organosilicon reagents poised to be eco-friendly alternatives for transition-metal carbonyls, have remained largely elusive. They have mostly been explored theoretically and/or through low-temperature matrix isolation studies, but their instability had typically precluded isolation under ambient conditions. Here we present the synthesis, isolation and full characterization of stable silyl-substituted silicon-carbonyl complexes, along with bonding analysis. Initial reactivity investigations showed examples of CO liberation, which could be induced either thermally or photochemically, as well as substitution and functionalization of the CO moiety. Importantly, the complexes exhibit strong Si-CO bonding, with CO→Si σ-donation and Si→CO π-backbonding, which is reminiscent of transition-metal carbonyls. This similarity between the abundant semi-metal silicon and rare transition metals may provide new opportunities for the development of silicon-based catalysis.
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Affiliation(s)
- Dominik Reiter
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Garching bei München, Germany
| | - Richard Holzner
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Garching bei München, Germany
| | - Amelie Porzelt
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Garching bei München, Germany
| | - Philipp Frisch
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Garching bei München, Germany
| | - Shigeyoshi Inoue
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Garching bei München, Germany.
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47
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Peltier JL, Tomás-Mendivil E, Tolentino DR, Hansmann MM, Jazzar R, Bertrand G. Realizing Metal-Free Carbene-Catalyzed Carbonylation Reactions with CO. J Am Chem Soc 2020; 142:18336-18340. [DOI: 10.1021/jacs.0c09938] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jesse L. Peltier
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, United States
| | - Eder Tomás-Mendivil
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, United States
- Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country (UPV-EHU), Donostia-San Sebastián, 20018 Gipuzkoa, Spain
| | - Daniel R. Tolentino
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, United States
| | - Max M. Hansmann
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, United States
| | - Rodolphe Jazzar
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, United States
| | - Guy Bertrand
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, United States
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48
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Espinosa Ferao A, García Alcaraz A, Zaragoza Noguera S, Streubel R. Terminal Phosphinidene Complex Adducts with Neutral and Anionic O-Donors and Halides and the Search for a Differentiating Bonding Descriptor. Inorg Chem 2020; 59:12829-12841. [DOI: 10.1021/acs.inorgchem.0c01874] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Arturo Espinosa Ferao
- Departamento de Quı́mica Orgánica, Facultad de Quı́mica, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain
| | - Antonio García Alcaraz
- Departamento de Quı́mica Orgánica, Facultad de Quı́mica, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain
| | - Salvador Zaragoza Noguera
- Departamento de Quı́mica Orgánica, Facultad de Quı́mica, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain
| | - Rainer Streubel
- Institut für Anorganische Chemie, Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
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49
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Delaude L. The Chemistry of Azolium‐Carboxylate Zwitterions and Related Compounds: a Survey of the Years 2009–2020. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Lionel Delaude
- Laboratory of CatalysisMolSys Research UnitInstitut de Chimie Organique (B6a)Université de Liège Allée du six Août 13 4000 Liège Belgium
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50
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Ghosh B, Phukan AK. Probing the potential of metalla-N-heterocyclic carbenes towards activation of enthalpically strong bonds. Dalton Trans 2020; 49:9505-9515. [PMID: 32608419 DOI: 10.1039/d0dt01363c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Density functional theory calculations are employed to explore the reactivity of metalla-N-heterocyclic carbenes (MNHCs) towards activation of a variety of small molecules (H2, NH3, PH3, SiH3Ph and CH4). All the MNHCs considered are found to have a stable singlet ground state and possess suitable electronic properties for their application in small molecule activation. The calculated energy barriers of E-H (E = H, C, N, Si, P) activation for the MNHCs are found to be in agreement with those of the experimentally evaluated cyclic alkyl(amino)carbene (CAAC) and diamidocarbenes (DACs), thereby indicating the activating effect of the incorporation of an ancillary metal center within a cyclic NHC, and highlighting a new, underexplored strategy in achieving difficult bond activations with carbenes.
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Affiliation(s)
- Bijoy Ghosh
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India.
| | - Ashwini K Phukan
- Department of Chemical Sciences, Tezpur University, Napaam 784028, Assam, India.
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