1
|
Werner L, Radius U. NHC aluminum chemistry on the rise. Dalton Trans 2024. [PMID: 39225565 DOI: 10.1039/d4dt01660b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
This perspective highlights recent developments of the use of N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino)carbenes (cAACs) in alane and aluminum organyl chemistry. Especially in the last few years this flourishing research field led to some remarkable discoveries including various substitution patterns at the central aluminum atom, different oxidation states, neutral and charged compounds with varying coordination numbers and unique reactivities. Thereby NHCs play a vital role in the stabilization of these otherwise highly reactive compounds, which would not be realizable without the use of this intriguing class of ligands. Nevertheless, main group hydrides and especially NHC ligated alanes also tend to undergo NHC decomposition reactions, which are part of ongoing research and provide important information for NHC research in general.
Collapse
Affiliation(s)
- Luis Werner
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Udo Radius
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| |
Collapse
|
2
|
Werner L, Hagn J, Walpuski J, Radius U. Aluminum(III) Cations [(NHC) ⋅ AlMes 2 ] + : Synthesis, Characterization, and Application in FLP-Chemistry. Angew Chem Int Ed Engl 2023:e202312111. [PMID: 37877231 DOI: 10.1002/anie.202312111] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 10/24/2023] [Accepted: 10/25/2023] [Indexed: 10/26/2023]
Abstract
The three-coordinate aluminum cations ligated by N-heterocyclic carbenes (NHCs) [(NHC) ⋅ AlMes2 ]+ [B(C6 F5 )4 ]- (NHC=IMeMe 4, IiPrMe 5, IiPr 6, Mes=2,4,6-trimethylphenyl) were prepared via hydride abstraction of the alanes (NHC) ⋅ AlHMes2 (NHC=IMeMe 1, IiPrMe 2, IiPr 3) using [Ph3 C]+ [B(C6 F5 )4 ]- in toluene as hydride acceptor. If this reaction was performed in diethyl ether, the corresponding four-coordinate aluminum etherate cations [(NHC) ⋅ AlMes2 (OEt2 )]+ [B(C6 F5 )4 ]- 7-9 (NHC=IMeMe 7, IiPrMe 8, IiPr 9) were isolated. According to a theoretical and experimental assessment of the Lewis-acidity of the [(IMeMe ) ⋅ AlMes2 ]+ cation is the acidity larger than that of B(C6 F5 )3 and of similar magnitude as reported for Al(C6 F5 )3 . The reaction of [(IMeMe ) ⋅ AlMes2 ]+ [B(C6 F5 )4 ]- 4 with the sterically less demanding, basic phosphine PMe3 afforded a mixed NHC/phosphine stabilized cation [(IMeMe ) ⋅ AlMes2 (PMe3 )]+ [B(C6 F5 )4 ]- 10. Equimolar mixtures of 4 and the sterically more demanding PCy3 gave a frustrated Lewis-pair (FLP), i.e., [(IMeMe ) ⋅ AlMes2 ]+ [B(C6 F5 )4 ]- /PCy3 FLP-11, which reacts with small molecules such as CO2 , ethene, and 2-butyne.
Collapse
Affiliation(s)
- Luis Werner
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Julika Hagn
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Janis Walpuski
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Udo Radius
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| |
Collapse
|
3
|
Merschel A, Vishnevskiy YV, Neumann B, Stammler HG, Ghadwal RS. Highly Soluble Cyclic Organoalanes Based on Anionic Dicarbenes. Chemistry 2023; 29:e202301037. [PMID: 37293882 DOI: 10.1002/chem.202301037] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/16/2023] [Accepted: 06/09/2023] [Indexed: 06/10/2023]
Abstract
Cyclic organoalane compounds [(ADCAr )AlH2 ]2 (ADCAr = ArC{(DippN)C}2 ; Dipp = 2,6-iPr2 C6 H3 ; Ar = Ph or 4-PhC6 H4 (Bp)) based on anionic dicarbene (ADC) frameworks have been reported as crystalline solids. Treatments of Li(ADCAr ) with LiAlH4 at room temperature afford [(ADCAr )AlH2 ]2 with the concomitant release of LiH. Compounds [(ADCAr )AlH2 ]2 are stable crystalline solids and are freely soluble in common organic solvents. They are annulated tricyclic compounds with an almost planar central C4 Al2 -core embedded between two peripheral 1,3-imidazole (C3 N2 ) rings. At room temperature, [(ADCPh )AlH2 ]2 readily reacts with CO2 to form two- and four-fold hydroalumination products [(ADCPh )AlH(OCHO)]2 and [(ADCPh )Al(OCHO)2 ]2 , respectively. Further hydroalumination reactivity of [(ADCPh )AlH2 ]2 has been shown with isocyanate (RNCO) and isothiocyanate (RNCS) species (R=alkyl or aryl group). All compounds have been characterized by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction.
Collapse
Affiliation(s)
- Arne Merschel
- Molecular Inorganic Chemistry and Catalysis, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Yury V Vishnevskiy
- Molecular Inorganic Chemistry and Catalysis, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| |
Collapse
|
4
|
Pollard VA, Fuentes MA, Robertson SD, Weetman C, Kennedy AR, Brownlie J, Angus FJ, Smylie C, Mulvey RE. Reactivity studies and structural outcomes of a bulky dialkylaluminium amide in the presence of the N-heterocyclic carbene, ItBu. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
5
|
Roy MMD, Omaña AA, Wilson ASS, Hill MS, Aldridge S, Rivard E. Molecular Main Group Metal Hydrides. Chem Rev 2021; 121:12784-12965. [PMID: 34450005 DOI: 10.1021/acs.chemrev.1c00278] [Citation(s) in RCA: 124] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.
Collapse
Affiliation(s)
- Matthew M D Roy
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Alvaro A Omaña
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Andrew S S Wilson
- Department of Chemistry, University of Bath, Avon BA2 7AY, United Kingdom
| | - Michael S Hill
- Department of Chemistry, University of Bath, Avon BA2 7AY, United Kingdom
| | - Simon Aldridge
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| |
Collapse
|
6
|
Yuvaraj K, Carpentier A, Smith CD, Maron L, Jones C. C-N and C-H Activation of an N-Heterocyclic Carbene by Magnesium(II) Hydride and Magnesium(I) Complexes. Inorg Chem 2021; 60:6065-6072. [PMID: 33793217 DOI: 10.1021/acs.inorgchem.1c00552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Reactions of the hindered N-heterocyclic carbene, :C{(MesNCH)2} (IMes; Mes = mesityl), with a series of β-diketiminatomagnesium(II) hydride and dimagnesium(I) complexes were carried out at 80 °C. The reactions involving the magnesium hydrides, [{(ArNacnac)Mg(μ-H)}2] [ArNacnac = [(ArNCMe)2CH]-, where Ar = 2,6-diethylphenyl (Dep) or 2,6-diisopropylphenyl (Dip)], proceeded via activation of an exocyclic C-N bond of IMes, giving magnesium imidazolyl compounds [(ArNacnac)Mg(μ-H)(μ-Imid)Mg(ArNacnac)] (Imid = [NC2H2N(Mes)C]-) and mesitylene. A low-yield IMes methyl C-H activation product, [(DepNacnac)Mg(IMes-H)], was also obtained, via H2 elimination, from the reaction between IMes and [{(DepNacnac)Mg(μ-H)}2]. Reactions between IMes and dimagnesium(I) compounds [{(ArNacnac)Mg}2] [Ar = 2,6-dimethylphenyl (Xyl) or Mes] afforded isostructural C-H activation products [(ArNacnac)Mg(IMes-H)] but in higher yields. Density functional theory calculations suggest that the reactions do not progress via stable adduct complex intermediates, which are sterically inaccessible.
Collapse
Affiliation(s)
- K Yuvaraj
- School of Chemistry, Monash University, P.O. Box 23, Melbourne, Victoria 3800, Australia
| | - Ambre Carpentier
- Université de Toulouse, CNRS, INSA, UPS, UMR 5215, LPCNO, 135 Avenue de Rangueil, Toulouse F-31077, France
| | - Cory D Smith
- School of Chemistry, Monash University, P.O. Box 23, Melbourne, Victoria 3800, Australia
| | - Laurent Maron
- Université de Toulouse, CNRS, INSA, UPS, UMR 5215, LPCNO, 135 Avenue de Rangueil, Toulouse F-31077, France
| | - Cameron Jones
- School of Chemistry, Monash University, P.O. Box 23, Melbourne, Victoria 3800, Australia
| |
Collapse
|
7
|
Gruden E, Tavčar G. Synthesis and characterization of partially substituted NHC supported alane adducts using triflate or chloride salts. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.115009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Bolley A, Specklin D, Dagorne S. NHC-stabilized Al(III) and Ga(III) cationic alkyls: Synthesis, structure and use in hydrosilylation catalysis. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.114956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
9
|
Trose M, Cordes DB, Slawin AMZ, Stasch A. A Facile Synthesis of Robinson's NHC‐Stabilised Diborane(4). Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Michael Trose
- EaStCHEM School of Chemistry University of St Andrews North Haugh KY16 9ST St Andrews UK
| | - David B. Cordes
- EaStCHEM School of Chemistry University of St Andrews North Haugh KY16 9ST St Andrews UK
| | - Alexandra M. Z. Slawin
- EaStCHEM School of Chemistry University of St Andrews North Haugh KY16 9ST St Andrews UK
| | - Andreas Stasch
- EaStCHEM School of Chemistry University of St Andrews North Haugh KY16 9ST St Andrews UK
| |
Collapse
|
10
|
Hock A, Werner L, Riethmann M, Radius U. Bis‐NHC Aluminium and Gallium Dihydride Cations [(NHC)
2
EH
2
]
+
(E = Al, Ga). Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Andreas Hock
- Institut für Anorganische Chemie Julius‐Maximilians‐Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Luis Werner
- Institut für Anorganische Chemie Julius‐Maximilians‐Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Melanie Riethmann
- Institut für Anorganische Chemie Julius‐Maximilians‐Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Udo Radius
- Institut für Anorganische Chemie Julius‐Maximilians‐Universität Würzburg Am Hubland 97074 Würzburg Germany
| |
Collapse
|
11
|
Hock A, Werner L, Luz C, Radius U. N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene adducts of gallium hydrides, gallium chlorides and gallium hydrochlorides. Dalton Trans 2020; 49:11108-11119. [PMID: 32743616 DOI: 10.1039/d0dt02070b] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis and characterization of N-heterocyclic carbene (NHC) and cyclic (alkyl)(amino)carbene (cAAC) gallane and chlorogallane adducts of the type (NHC)·GaH3 (NHC = Me2ImMe1, iPr2Im 2, iPr2ImMe3 and Dipp2ImH4; Me2ImMe = 1,3,4,5-tetra-methyl-imidazolin-2-ylidene; R2Im = 1,3-di-organyl-imidazolin-2-ylidene; Dipp = 2,6-diisopropylphenyl; Dipp2ImH = 1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-ylidene), (NHC)·GaH2Cl (NHC = iPr2ImMe9, Dipp2Im 10 and Dipp2ImH11; iPr2ImMe = 1,3 diisopropyl-4,5-dimethyl-imidazolin-2-ylidene), (NHC)·GaHCl2 (NHC = iPr2ImMe12, Dipp2Im 13 and Dipp2ImH14) and (cAACMe)·GaHCl215 is reported. Compounds 1-3 and 9-11 are unstable in solution as heating to the boiling temperature of toluene (110 °C) leads to decomposition into elemental gallium and the corresponding dihydroaminal NHC-H2. The reaction of the mono-NHC adducts with a second equivalent of NHC also afforded decomposition and formation of NHC-H2, whereas the reaction of the NHC-stabilized gallanes with one equivalent cAACMe leads to an insertion of the cAACMe carbene carbon atom into the Ga-H bond. The synthesis and characterization of (NHC)·GaH2(cAACMeH) (NHC = Me2ImMe5, iPr2ImMe6 and Dipp2Im 7), the products of an oxidative addition of (NHC)·GaH3 to cAACMe, are presented. The adduct (Dipp2ImH)·GaH34 reacts with two equivalents of cAACMe under the release of Dipp2ImH and insertion of two cAACMe molecules into the Ga-H bond to give the bisalkylgallane (cAACMeH)2GaH 8. If one or two hydrogen atoms of the NHC gallane adducts are replaced with an electron-withdrawing chloride substituent, a selective insertion of cAACMe into the Ga-H bond occurs only for the adducts of sterically less demanding NHCs such as iPr2ImMe. The reaction of cAACMe with (iPr2ImMe)·GaH2Cl 9 and (iPr2ImMe)·GaHCl212 afforded (iPr2ImMe)·GaHCl(cAACMeH) 16 and (iPr2ImMe)·GaCl2(cAACMeH) 17. The reaction of cAACMe with (NHC)·GaHCl2 and (NHC)·GaH2Cl (NHC = Dipp2Im, Dipp2ImH), adducts of the sterically more demanding NHCs, leads to an extrusion of the NHC to (cAACMe)·GaHCl215 and (cAACMeH)2GaCl 18.
Collapse
Affiliation(s)
- Andreas Hock
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Luis Werner
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Christian Luz
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Udo Radius
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| |
Collapse
|
12
|
Franz D, Inoue S. Cationic Complexes of Boron and Aluminum: An Early 21st Century Viewpoint. Chemistry 2018; 25:2898-2926. [PMID: 30113744 DOI: 10.1002/chem.201803370] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Indexed: 01/03/2023]
Abstract
Boron and aluminum are lighter Group 13 elements, found in daily life commodities, and considered environmentally benign. Nevertheless, they markedly differ in their elemental properties (e.g., metal character, atomic radius). The use of Lewis acidic complexes of boron and aluminum for methods of bond activation and catalysis (e.g., hydrogenation of unsaturated substrates, polymerization of olefins and epoxides) is quickly expanding. The introduction of cationic charge may boost the metalloid-centered Lewis acidity and allow for its fine-tuning particularly with regard to preference for "hard" or "soft" Lewis bases (i.e., substrates). Especially the isolation of low-coordinate cations (number of ligand atoms smaller than four) demands elaborate techniques of thermodynamic and kinetic stabilization (i.e., electronic saturation and steric shielding) by a ligand system. Furthermore, the properties of the solvent and the counteranion must be considered with care. Here, selected examples of boron and aluminum cations are described.
Collapse
Affiliation(s)
- Daniel Franz
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstr. 4, 85748, Garching bei München, Germany
| | - Shigeyoshi Inoue
- Department of Chemistry, WACKER-Institute of Silicon Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstr. 4, 85748, Garching bei München, Germany
| |
Collapse
|