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Dissanayake D, Forsyth C, Vidović D. Synthesis, characterisation and reactivity studies of chiral β-diketiminate-like supported aluminium Lewis acid complexes towards difficult Diels Alder cycloadditions. Dalton Trans 2023; 52:4063-4076. [PMID: 36880570 DOI: 10.1039/d3dt00206c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Synthesis and characterisation of several chiral, oxazoline containing β-diketiminate type ligand supported-aluminium compounds are reported. Together with 1 equiv. of Na(BArCl4) (ArCl = 3,5-Cl2-C6H3), these chiral Lewis acid complexes, which possess an "achiral end" and "chiral end" have been successfully utilised as catalysts in asymmetric Diels-Alder reactions of 1,3-cyclohexadiene and several different chalcones. Systematic increase in the steric demand of the ligand's "achiral end" of these complexes resulted in enhanced enantioinduction for the cyclisation of 1,3-cyclohexadiene and chalcone. Further structural modifications of the "chiral end" clearly established that having a tert-butyl group connected to the stereogenic centre of the oxazoline fragment yielded the highest enantioselectivity value for the examined cyclisation. A substrate scope was then expanded using several different dienophiles (i.e. chalcones) generating an enantiomeric excess range of 24-68%.
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Affiliation(s)
| | - Craig Forsyth
- School of Chemistry, Monash University, Wellington Rd, Clayton VIC 3800, Australia.
| | - Dragoslav Vidović
- School of Chemistry, Monash University, Wellington Rd, Clayton VIC 3800, Australia.
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2
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Rinke P, Görls H, Kretschmer R. Calcium and Magnesium Bis(β-diketiminate) Complexes: Impact of the Alkylene Bridge on Schlenk-Type Rearrangements. Inorg Chem 2021; 60:5310-5321. [PMID: 33667337 DOI: 10.1021/acs.inorgchem.1c00301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Dinuclear heteroleptic alkaline-earth-metal complexes are interesting synthetic targets because the close proximity of two metals allows for cooperative effects. However, these complexes are also prone to undergoing Schlenk-type rearrangements, affording less-active homoleptic complexes. Here we present the metalation of bis(β-diketimine) ligands possessing flexible bridging groups, i.e., 1,2-ethylene, 1,3-propylene, and trans-1,2-cyclohexylene, using calcium and magnesium precursors. Four mononuclear homoleptic calcium complexes were obtained, highlighting the pronounced tendency of calcium to undergo Schlenk-like redistributions. In the case of magnesium, however, the bridging group plays a crucial role, yielding seven dinuclear heteroleptic complexes but also one mononuclear and one dinuclear homoleptic complexes. In addition, a trinuclear mixed heteroleptic-homoleptic magnesium complex, which is a rare example of an intermediate of the Schlenk equilibrium, was isolated.
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Affiliation(s)
- Philipp Rinke
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Robert Kretschmer
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany.,Jena Center for Soft Matter, Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany
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3
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Wang X, Meng Y, Hou L, Wang Y, Wang W. Systematic and efficient synthesis of β-diketiminato aluminum halides and their structural characterization. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.152942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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4
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Li Y, Dang Y, Li D, Pan H, Zhang L, Wang L, Cao Z, Li Y. Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides. Organometallics 2021. [DOI: 10.1021/acs.organomet.0c00733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Yafei Li
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Yan Dang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Dawei Li
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Huifen Pan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Liang Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Li Wang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Zhu Cao
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Yahong Li
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
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5
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Kysliak O, Görls H, Kretschmer R. Cooperative Bond Activation by a Bimetallic Main-Group Complex. J Am Chem Soc 2021; 143:142-148. [PMID: 33356229 DOI: 10.1021/jacs.0c12166] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Inspired by natural metalloenzymes that efficiently catalyze a variety of transformations, chemists have developed large numbers of dinuclear transition-metal complexes with extraordinary properties and reactivity patterns. For main-group element compounds, however, metal-metal cooperativity is much less explored. Here we present the synthesis and characterization of a room-temperature-stable compound with two separated two-coordinated gallium(I) centers possessing both a lone pair of electrons and a vacant orbital, reminiscent of singlet carbenes. This species displays enhanced reactivity compared to its mononuclear counterpart due to bimetallic cooperativity that allows for the facile activation of strong C-F bonds across the gallium-gallium bond. Two mechanistic scenarios of the cooperative bond activation have been identified by DFT and DLPNO-CCSD(T) calculations.
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Affiliation(s)
- Oleksandr Kysliak
- Institute of Inorganic and Analytical Chemistry (IAAC), Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry (IAAC), Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Robert Kretschmer
- Institute of Inorganic and Analytical Chemistry (IAAC), Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany
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6
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Rösch A, Seifert F, Vass V, Görls H, Kretschmer R. Synthesis, structure, and catalytic activity of dinuclear aluminium bis(amidinate) and bis(guanidinate) complexes. NEW J CHEM 2021. [DOI: 10.1039/d0nj05007e] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The ring-opening polymerization grand prix: Bis(amidinate)s outpaced their bis(guanidinate) competitors and won the race, while the drivers’ engines using acidic co-initiators collapsed before take-off.
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Affiliation(s)
- Andreas Rösch
- Institute of Inorganic Chemistry
- University of Regensburg
- 93053 Regensburg
- Germany
| | - Fabian Seifert
- Institute of Inorganic and Analytical Chemistry
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
| | - Valentin Vass
- Institute of Inorganic Chemistry
- University of Regensburg
- 93053 Regensburg
- Germany
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
| | - Robert Kretschmer
- Institute of Inorganic and Analytical Chemistry
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Jena Center for Soft Matter (JCSM)
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Rösch A, Herzog CM, Schreiner SHF, Görls H, Kretschmer R. Ditopic bis( N, N', N'-substituted 1,2-ethanediamine) ligands: synthesis and coordination chemistry. Dalton Trans 2020; 49:13818-13828. [PMID: 33001083 DOI: 10.1039/d0dt03124k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The synthesis of two different types of bis(N,N',N'-substituted 1,2-ethanediamine)s, bridged either through the secondary (type 1) or tertiary (type 2) amine groups is reported. Selected protio-ligands have been applied in subsequent metallation reactions using aluminium, magnesium, tin, and zinc sources allowing to isolate five mononuclear and eight dinuclear complexes. All complexes have been fully characterized and their solid-state structures have been studied by means of single-crystal X-ray diffraction analysis. Nine of the 13 complexes carry reactive alkyl, amide or hydride groups, which indicates their potential as catalysts or supports for (transition) metals.
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Affiliation(s)
- Andreas Rösch
- Institute of Inorganic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Christoph M Herzog
- Institute of Inorganic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Simon H F Schreiner
- Institute of Inorganic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry (IAAC), Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Robert Kretschmer
- Institute of Inorganic and Analytical Chemistry (IAAC), Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany and Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena Philosophenweg 7, 07743 Jena, Germany.
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8
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Rösch A, Schreiner SHF, Schüler P, Görls H, Kretschmer R. Magnesium bis(amidinate) and bis(guanidinate) complexes: impact of the ligand backbone and bridging groups on the coordination behaviour. Dalton Trans 2020; 49:13072-13082. [PMID: 32926063 DOI: 10.1039/d0dt01923b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A library of ten dinucleating bis(amidine) and bis(guanidine) ligands, in which the bridging groups, terminal rests, and backbone substituents were systematically altered, has been synthesized and subsequently applied in metallation reactions using three different magnesium sources. Eight Mg complexes could be isolated and fully characterized, and in seven cases their solid-state structure could be determined by means of single crystal X-ray diffraction analysis. The results evidence a versatile coordination behaviour, which ranges from the first dinuclear heteroleptic magnesium iodide complex to dinuclear homoleptic complexes. These findings indicate the crucial impact of both the ligand and the magnesium source not only on the accessibility of well-defined dinuclear complexes but also on the aggregation in solution and in the solid state.
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Affiliation(s)
- Andreas Rösch
- Institute of Inorganic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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9
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Peddarao T, Sarkar N, Nembenna S. Mono- and Bimetallic Aluminum Alkyl, Alkoxide, Halide and Hydride Complexes of a Bulky Conjugated Bis-Guanidinate(CBG) Ligand and Aluminum Alkyls as Precatalysts for Carbonyl Hydroboration. Inorg Chem 2020; 59:4693-4702. [PMID: 32157882 DOI: 10.1021/acs.inorgchem.9b03778] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tetra-aryl-substituted symmetrical conjugated bis-guanidine (CBG) ligands such as L1-3 (3H) [L(3H) = {(ArHN)(ArHN)C═N-C═NAr(NHAr)}; Ar = 2,6-Me2-C6H3 (L1(3H)), 2,6-Et2-C6H3 (L2(3H)), and 2,6-iPr2-C6H3 (L3(3H))] have been employed to synthesize a series of four- and six-membered aluminum heterocycles (1-8) for the first time. Generally, aluminum complexes bearing N,N'- chelated guanidinate and β-diketiminate/dipyrromethene ligand systems form four- and six-membered heterocycles, respectively. However, the conjugated bis-guanidine ligand has the capability of forming both four- and six-membered heterocycles possessing multimetal centers within the same molecule; this is due to the presence of three acidic protons, which can be easily deprotonated (at least two protons) upon treatment with metal reagents. Both mono- and dinuclear aluminum alkyls and mononuclear aluminum alkoxide, halide, and hydride complexes have been structurally characterized. Further, we have demonstrated the potential of mononuclear, six-membered CBG aluminum dialkyls in catalytic hydroboration of a broad range of aldehydes and ketones with pinacolborane (HBpin).
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Affiliation(s)
- Thota Peddarao
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Homi Bhabha National Institute (HBNI), Bhubaneswar 752 050, India
| | - Nabin Sarkar
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Homi Bhabha National Institute (HBNI), Bhubaneswar 752 050, India
| | - Sharanappa Nembenna
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), Homi Bhabha National Institute (HBNI), Bhubaneswar 752 050, India
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10
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Kretschmer R. Ligands with Two Monoanionic N,N-Binding Sites: Synthesis and Coordination Chemistry. Chemistry 2020; 26:2099-2119. [PMID: 31755598 PMCID: PMC7064907 DOI: 10.1002/chem.201903442] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/19/2019] [Indexed: 11/07/2022]
Abstract
Polytopic ligands have become ubiquitous in coordination chemistry because they grant access to a variety of mono- and polynuclear complexes of transition metals as well as rare-earth and main-group elements. Nitrogen-based ditopic ligands, in which two monoanionic N,N-binding sites are framed within one molecule, are of particular importance and are therefore the primary focus of this review. In detail, bis(amidine)s, bis(guanidine)s, bis(β-diimine)s, bis(aminotroponimine)s, bis(pyrrolimine)s, and miscellaneous bis(N,N-chelating) ligands are reviewed. In addition to the general synthetic protocols, the application of these ligands is discussed along with their coordination chemistry, the multifarious binding modes, and the ability of these ligands to bridge two (or more) metal(loids).
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Affiliation(s)
- Robert Kretschmer
- Junior Professorship Inorganic Chemistry of Catalysis, Institute of Inorganic and Analytical ChemistryFriedrich Schiller University JenaHumboldtstrasse 807743JenaGermany
- Jena Center for Soft Matter (JCSM)Friedrich Schiller University JenaPhilosophenweg 707743JenaGermany
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11
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Kysliak O, Görls H, Kretschmer R. Salt metathesis as an alternative approach to access aluminium(i) and gallium(i) β-diketiminates. Dalton Trans 2020; 49:6377-6383. [PMID: 32350497 DOI: 10.1039/d0dt01342k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aluminium(i) and gallium(i) β-diketiminates are accessed by a new route that provides better overall yields. In the case of aluminium it is also much faster, but some molecules turn into a dead end and merge into a dinuclear aluminium(iii) hydride.
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Affiliation(s)
- Oleksandr Kysliak
- Institute of Inorganic and Analytical Chemistry (IAAC)
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry (IAAC)
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
| | - Robert Kretschmer
- Institute of Inorganic and Analytical Chemistry (IAAC)
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Jena Center for Soft Matter (JCSM)
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