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Griffin LP, Ellwanger MA, Clark J, Myers WK, Roper AF, Heilmann A, Aldridge S. Bis(Aluminyl)Magnesium: A Source of Nucleophilic or Radical Aluminium-Centred Reactivity. Angew Chem Int Ed Engl 2024; 63:e202405053. [PMID: 38536728 DOI: 10.1002/anie.202405053] [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: 03/13/2024] [Indexed: 04/23/2024]
Abstract
The homoleptic magnesium bis(aluminyl) compound Mg[Al(NON)]2 (NON=4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) can be accessed from K2[Al(NON)]2 and MgI2 and shown to possess a non-linear geometry (∠Al-Mg-Al=164.8(1)°) primarily due to the influence of dispersion interactions. This compound acts a four-electron reservoir in the reductive de-fluorination of SF6, and reacts thermally with polar substrates such as MeI via nucleophilic attack through aluminium, consistent with the QT-AIM charges calculated for the metal centres, and a formal description as a Al(I)-Mg(II)-Al(I) trimetallic. On the other hand, under photolytic activation, the reaction with 1,5-cyclooctadiene leads to the stereo-selective generation of transannular cycloaddition products consistent with radical based chemistry, emphasizing the covalent nature of the Mg-Al bonds and a description as a Al(II)-Mg(0)-Al(II) synthon. Consistently, photolysis of Mg[Al(NON)]2 in hexane in the absence of COD generates [Al(NON)]2 together with magnesium metal.
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Affiliation(s)
- Liam P Griffin
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Mathias A Ellwanger
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Jonathon Clark
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - William K Myers
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - Aisling F Roper
- 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
| | - Simon Aldridge
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
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2
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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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3
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Lee TC, Tong Y, Fu WC. Advances in Continuous Flow Fluorination Reactions. Chem Asian J 2023; 18:e202300723. [PMID: 37707985 DOI: 10.1002/asia.202300723] [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: 08/17/2023] [Revised: 09/12/2023] [Accepted: 09/14/2023] [Indexed: 09/16/2023]
Abstract
Fluorination reactions are important in constructing organofluorine motifs, which contribute to favorable biological properties in pharmaceuticals and agrochemicals. However, fluorination reagents and reactions are associated with various problems, such as their hazardous nature, high exothermicity, and poor selectivity and scalability. Continuous flow has emerged as a transformative technology to provide many advantages relative to batch syntheses. This review article summarizes recent continuous flow techniques that address the limitations and challenges of fluorination reactions. Approaches based on different flow techniques are discussed, including gas-liquid reactions, packed-bed reactors, in-line purifications, streamlined multistep synthesis, large-scale reactions well as flow photoredox- and electrocatalysis.
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Affiliation(s)
- Tsz Chun Lee
- Department of Chemistry, City University of Hong Kong, Tat Chee Ave, Kowloon, Hong Kong SAR, China
| | - Yi Tong
- Department of Chemistry, City University of Hong Kong, Tat Chee Ave, Kowloon, Hong Kong SAR, China
| | - Wai Chung Fu
- Department of Chemistry, City University of Hong Kong, Tat Chee Ave, Kowloon, Hong Kong SAR, China
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4
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Liu HY, Hill MS, Mahon MF, McMullin CL, Schwamm RJ. Seven-Membered Cyclic Diamidoalumanyls of Heavier Alkali Metals: Structures and C-H Activation of Arenes. Organometallics 2023; 42:2881-2892. [PMID: 37829511 PMCID: PMC10565898 DOI: 10.1021/acs.organomet.3c00323] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Indexed: 10/14/2023]
Abstract
Like the previously reported potassium-based system, rubidium and cesium reduction of [{SiNDipp}AlI] ({SiNDipp} = {CH2SiMe2NDipp}2) with the heavier alkali metals [M = Rb and Cs] provides dimeric group 1 alumanyl derivatives, [{SiNDipp}AlM]2. In contrast, similar treatment with sodium results in over-reduction and incorporation of a formal equivalent of [{SiNDipp}Na2] into the resultant sodium alumanyl species. The dimeric K, Rb, and Cs compounds display a variable efficacy toward the C-H oxidative addition of arene C-H bonds at elevated temperatures (Cs > Rb > K, 110 °C) to yield (hydrido)(organo)aluminate species. Consistent with the synthetic experimental observations, computational (DFT) assessment of the benzene C-H activation indicates that rate-determining attack of the Al(I) nucleophile within the dimeric species is facilitated by π-engagement of the arene with the electrophilic M+ cation, which becomes increasingly favorable as group 1 is descended.
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Affiliation(s)
- Han-Ying Liu
- Department of Chemistry, University
of Bath, Claverton
Down, Bath BA2 7AY, U.K.
| | - Michael S. Hill
- Department of Chemistry, University
of Bath, Claverton
Down, Bath BA2 7AY, U.K.
| | - Mary F. Mahon
- Department of Chemistry, University
of Bath, Claverton
Down, Bath BA2 7AY, U.K.
| | - Claire L. McMullin
- Department of Chemistry, University
of Bath, Claverton
Down, Bath BA2 7AY, U.K.
| | - Ryan J. Schwamm
- Department of Chemistry, University
of Bath, Claverton
Down, Bath BA2 7AY, U.K.
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5
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Sheldon DJ, Parr JM, Crimmin MR. Room Temperature Defluorination of Poly(tetrafluoroethylene) by a Magnesium Reagent. J Am Chem Soc 2023; 145:10486-10490. [PMID: 37154713 DOI: 10.1021/jacs.3c02526] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Perfluoroalkyl substances (PFAS) are pervasive in the environment. The largest single use material within the PFAS compound class is poly(tetrafluoroethylene) (PTFE), a robust and chemically resistant polymer. Despite their widespread use and serious concerns about their role as pollutants, methods for repurposing PFAS are rare. Here we show that a nucleophilic magnesium reagent reacts with PTFE at room temperature, generating a molecular magnesium fluoride which is easily separated from the surface-modified polymer. The fluoride in turn can be used to transfer the fluorine atoms to a small array of compounds. This proof-of-concept study demonstrates that the atomic fluorine content of PTFE can be harvested and reused in chemical synthesis.
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Affiliation(s)
- Daniel J Sheldon
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, U.K
| | - Joseph M Parr
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, U.K
| | - Mark R Crimmin
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, U.K
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Sheldon DJ, Crimmin MR. Repurposing of F-gases: challenges and opportunities in fluorine chemistry. Chem Soc Rev 2022; 51:4977-4995. [PMID: 35616085 PMCID: PMC9207706 DOI: 10.1039/d1cs01072g] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Indexed: 11/24/2022]
Abstract
Fluorinated gases (F-gases) are routinely employed as refrigerants, blowing agents, and electrical insulators. These volatile compounds are potent greenhouse gases and consequently their release to the environment creates a significant contribution to global warming. This review article seeks to summarise: (i) the current applications of F-gases, (ii) the environmental issues caused by F-gases, (iii) current methods of destruction of F-gases and (iv) recent work in the field towards the chemical repurposing of F-gases. There is a great opportunity to tackle the environmental and sustainability issues created by F-gases by developing reactions that repurpose these molecules.
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Affiliation(s)
- Daniel J Sheldon
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK.
| | - Mark R Crimmin
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK.
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7
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Liu P, Cai K, Liu M, Xu M, Zhao T. Deep eutectic solvents with multiple hydroxyl sites for efficient and reversible absorption of SF6. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Kim S, Nagorny P. Electrochemical Synthesis of Glycosyl Fluorides Using Sulfur(VI) Hexafluoride as the Fluorinating Agent. Org Lett 2022; 24:2294-2298. [PMID: 35298181 PMCID: PMC10543653 DOI: 10.1021/acs.orglett.2c00431] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This manuscript describes the electrochemical synthesis of 17 different glycosyl fluorides in 73-98% yields on up to a 5 g scale that relies on the use of SF6 as an inexpensive and safe fluorinating agent. Cyclic voltammetry and related mechanistic studies carried out subsequently suggest that the active fluorinating species generated through the cathodic reduction of SF6 are transient under these reductive conditions and that the sulfur and fluoride byproducts are effectively scavenged by Zn(II) to generate benign salts.
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Affiliation(s)
- Sungjin Kim
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Pavel Nagorny
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Pan X, Talavera M, Scholz G, Braun T. Chlorodefluorination of Fluoromethanes and Fluoroolefins at a Lewis Acidic Aluminum Fluoride. ChemCatChem 2022. [DOI: 10.1002/cctc.202200029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Xinzi Pan
- Humboldt-Universitat zu Berlin Department of Chemistry GERMANY
| | - Maria Talavera
- Humboldt-Universitat zu Berlin Department of Chemistry GERMANY
| | - Gudrun Scholz
- Humboldt-Universitat zu Berlin Department of Chemistry GERMANY
| | - Thomas Braun
- Humboldt University Chemistry Brook-Taylor Str. 2 12489 Berlin GERMANY
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Dirican D, Talavera M, Braun T. Fluorination Reactions at a Platinum Carbene Complex: Reaction Routes to SF 3 , S(=O)F and Fluorido Complexes. Chemistry 2021; 27:17707-17712. [PMID: 34634177 PMCID: PMC9298267 DOI: 10.1002/chem.202103311] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Indexed: 01/10/2023]
Abstract
The electron-rich Pt complex [Pt(IMes)2 ] (IMes: [1,3-bis(2,4,6-trimethylphenyl)-2-imidazolinylidine]) can be used as precursor for the syntheses of a variety of fluorido ligand containing compounds. The sulfur fluoride SF4 undergoes a rapid oxidative addition at Pt0 to yield trans-[Pt(F)(SF3 )(IMes)2 ]. A photolytic reaction of SF6 at [Pt(IMes)2 ] in the presence of IMes gave the fluorido complexes trans-[Pt(F)2 (IMes)2 ] and trans-[Pt(F)(SF3 )(IMes)2 ] along with trans-[Pt(F)(SOF)(IMes)2 ] and trans-[Pt(F)(IMes')(IMes)] (IMes': cyclometalated IMes ligand), the latter being products produced by reaction with adventitious water. trans-[Pt(F)(SOF)(IMes)2 ] and trans-[Pt(F)2 (IMes)2 ] were synthesized independently by treatment of [Pt(IMes)2 ] with SOF2 or XeF2 . A reaction of [Pt(IMes)2 ] with a HF source gave trans-[Pt(H)(F)(IMes)2 ], and an intermediate bifluorido complex trans-[Pt(H)(FHF)(IMes)2 ] was identified. Compound trans-[Pt(H)(F)(IMes)2 ] converts in the presence of CsF into trans-[Pt(F)(IMes')(IMes)].
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Affiliation(s)
- Dilcan Dirican
- Humboldt-Universität zu Berlin Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany
| | - Maria Talavera
- Humboldt-Universität zu Berlin Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany
| | - Thomas Braun
- Humboldt-Universität zu Berlin Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany
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11
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Huang S, Wang Y, Hu C, Yan X. Nucleophilic Activation of Sulfur Hexafluoride by N-Heterocyclic Carbenes and N-Heterocyclic Olefins: A Computational Study. Chem Asian J 2021; 16:2687-2693. [PMID: 34320272 DOI: 10.1002/asia.202100770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/26/2021] [Indexed: 11/10/2022]
Abstract
Sulfur hexafluoride (SF6 ) is considered as a potent greenhouse gas, whose effective degradation is challenging. Here we report a computational study on the nucleophilic activation of sulfur hexafluoride by N-heterocyclic carbenes and N-heterocyclic olefins. The result shows that the activation of SF6 is both thermodynamically and kinetically favorable at mild condition using NHOs with fluoro-substituted azolium and sulfur pentafluoride anion being formed. The Gibbs free energy barrier during the activation of SF6 has a linear relationship with the energy of HOMO of substrates, which could be a guideline for applying those compounds that feature higher energy in HOMO to activate SF6 in high efficiency.
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Affiliation(s)
- Shiqing Huang
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
| | - Yedong Wang
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
| | - Chubin Hu
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
| | - Xiaoyu Yan
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
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