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Davison N, Hemingway JM, Waddell PG, Lu E. Lithium, sodium and potassium enolate aggregates and monomers: syntheses and structures. Dalton Trans 2024; 53:4719-4728. [PMID: 38362928 DOI: 10.1039/d4dt00211c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
In this Article, we report the syntheses and comparative structural studies of lithium, sodium, and potassium anthracen-9-yl enolates, as their aggregates (Li, Na: hexamer; K: tetramer) and ligand-stabilized monomers (for Li and Na). The monomers add new members to the rare collection of group-1 metal monomeric enolates. Moreover, the series covers different group-1 metal cations (Li+, Na+ and K+) and aggregate sizes, allowing comparative structural studies to elucidate how the metal identity and aggregate size influence the enolate structure.
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Affiliation(s)
- Nathan Davison
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Jack M Hemingway
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Paul G Waddell
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Erli Lu
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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2
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Davison N, Waddell PG, Lu E. Reduction of K + or Li + in the Heterobimetallic Electride K +[LiN(SiMe 3) 2]e . J Am Chem Soc 2023; 145:17007-17012. [PMID: 37478322 PMCID: PMC10416298 DOI: 10.1021/jacs.3c06066] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Indexed: 07/23/2023]
Abstract
Given their very negative redox potential (e.g., Li+ → Li(0), -3.04 V; K+ → K(0), -2.93 V), chemical reduction of Group-1 metal cations is one of the biggest challenges in inorganic chemistry: they are widely accepted as irreducible in the synthetic chemistry regime. Their reduction usually requires harsh electrochemical conditions. Herein we suggest a new strategy: via a heterobimetallic electride intermediate and using the nonbinding "free" electron as reductant. Based on our previously reported K+[LiN(SiMe3)2]e- heterobimetallic electride, we demonstrate the reducibility of both K+ and Li+ cations. Moreover, we find that external Lewis base ligands, namely tris[2-(dimethylamino)ethyl]amine (Me6Tren) or 2,2,2-cryptand, can exert a level of reducing selectivity by preferably binding to Li+ (Me6Tren) or K+ (2,2,2-cryptand), hence pushing the electron to the other cation.
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Affiliation(s)
- Nathan Davison
- Chemistry−School of Natural
and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1
7RU, U.K.
| | - Paul G. Waddell
- Chemistry−School of Natural
and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1
7RU, U.K.
| | - Erli Lu
- Chemistry−School of Natural
and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1
7RU, U.K.
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3
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Davison N, McMullin CL, Zhang L, Hu SX, Waddell PG, Wills C, Dixon C, Lu E. Li vs Na: Divergent Reaction Patterns between Organolithium and Organosodium Complexes and Ligand-Catalyzed Ketone/Aldehyde Methylenation. J Am Chem Soc 2023; 145:6562-6576. [PMID: 36890641 PMCID: PMC10037334 DOI: 10.1021/jacs.3c01033] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
Organosodium chemistry is underdeveloped compared with organolithium chemistry, and all the reported organosodium complexes exhibit similar, if not identical, reactivity patterns to their lithium counterparts. Herein, we report a rare organosodium monomeric complex, namely, [Na(CH2SiMe3)(Me6Tren)] (1-Na) (Me6Tren: tris[2-(dimethylamino)ethyl]amine) stabilized by a tetra-dentate neutral amine ligand Me6Tren. Employing organo-carbonyl substrates (ketones, aldehydes, amides, ester), we demonstrated that 1-Na features distinct reactivity patterns compared with its lithium counterpart, [Li(CH2SiMe3)(Me6Tren)] (1-Li). Based on this knowledge, we further developed a ligand-catalysis strategy to conduct ketone/aldehyde methylenations, using [NaCH2SiMe3]∞ as the CH2 feedstock, replacing the widely used but hazardous/expensive C═O methylenation methods, such as Wittig, Tebbe, Julia/Julia-Kocieński, Peterson, and so on.
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Affiliation(s)
- Nathan Davison
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Claire L McMullin
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K
| | - Lu Zhang
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Shu-Xian Hu
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Paul G Waddell
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Corinne Wills
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Casey Dixon
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Erli Lu
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
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4
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Davison N, Quirk JA, Wills C, Dixon C, Waddell PG, Dawson JA, Lu E. Elucidating Solution-State Coordination Modes of Multidentate Neutral Amine Ligands with Group-1 Metal Cations: Variable-Temperature NMR Studies. Inorg Chem 2022; 61:15204-15212. [PMID: 36109881 PMCID: PMC9516690 DOI: 10.1021/acs.inorgchem.2c02457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Multidentate neutral amine ligands play vital roles in
coordination
chemistry and catalysis. In particular, these ligands are used to
tune the reactivity of Group-1 metal reagents, such as organolithium
reagents. Most, if not all, of these Group-1 metal reagent-mediated
reactions occur in solution. However, the solution-state coordination
behaviors of these ligands with Group-1 metal cations are poorly understood,
compared to the plethora of solid-state structural studies based on
single-crystal X-ray diffraction (SCXRD) studies. In this work, we
comprehensively mapped out the coordination modes with Group-1 metal
cations for three multidentate neutral amine ligands: tridentate 1,4,7-trimethyl-1,4,7-triazacyclononane
(Me3TACN), tetradentate tris[2-(dimethylamino)ethyl]amine
(Me6Tren), and hexadentate N,N′,N″-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane
(DETAN). The macrocycles in the Me3TACN and DETAN are identified
as the rigid structural directing motif, with the sidearms of DETAN
providing flexible “on-demand” coordination sites. In
comparison, the Me6Tren ligand features more robust coordination,
with the sidearms less likely to undergo the decoordinating–coordinating
equilibrium. This work will provide a guidance for coordination chemists
in applying these three ligands, in particular, the new DETAN ligand
to design metal complexes which suit their purposes. Combining variable-temperature nuclear
magnetic resonance
(VT NMR) and DFT calculations, this work elucidates the solution-state
coordination modes of three multidentate neutral amine ligands with
Group-1 metal cations. Our studies prove that two ligand-design building
blocks, that is, N-macrocycle (TACN) and N-sidearms, act as structure-dictating
and hemilabile coordinating sites, respectively. The concept could
be utilized in designing new catalytic systems, which anchor the metal
center on the macrocycle, while the sidearms serve as “on-demand”
protective coordination sites.
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Affiliation(s)
- Nathan Davison
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - James A. Quirk
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Corinne Wills
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Casey Dixon
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Paul G. Waddell
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - James A. Dawson
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Erli Lu
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
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5
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Davison N, Zhou K, Waddell PG, Wills C, Dixon C, Hu SX, Lu E. Versatile Coordination Modes of Multidentate Neutral Amine Ligands with Group 1 Metal Cations. Inorg Chem 2022; 61:3674-3682. [PMID: 35148099 PMCID: PMC9097481 DOI: 10.1021/acs.inorgchem.1c03786] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Indexed: 12/30/2022]
Abstract
This work comprehensively investigated the coordination chemistry of a hexa-dentate neutral amine ligand, namely, N,N',N"-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane (DETAN), with group-1 metal cations (Li+, Na+, K+, Rb+, Cs+). Versatile coordination modes were observed, from four-coordinate trigonal pyramidal to six-coordinate trigonal prismatic, depending on the metal ionic radii and metal's substituent. For comparison, the coordination chemistry of a tetra-dentate tris-[2-(dimethylamino)ethyl]amine (Me6Tren) ligand was also studied. This work defines the available coordination modes of two multidentate amine ligands (DETAN and Me6Tren), guiding future applications of these ligands for pursuing highly reactive and elusive s-block and rare-earth metal complexes.
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Affiliation(s)
- Nathan Davison
- Chemistry-School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne, United Kingdom, NE1 7RU
| | - Ke Zhou
- College
of Chemistry and Environmental Science & Shaanxi Key Laboratory
of Catalysis & Institute of Theoretical and Computational Chemistry, Shaanxi University of Technology. Hanzhong 723000, Shaanxi Province, China
| | - Paul G. Waddell
- Chemistry-School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne, United Kingdom, NE1 7RU
| | - Corinne Wills
- Chemistry-School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne, United Kingdom, NE1 7RU
| | - Casey Dixon
- Chemistry-School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne, United Kingdom, NE1 7RU
| | - Shu-Xian Hu
- Beijing
Computational Science Research Center, Beijing 100193, China
| | - Erli Lu
- Chemistry-School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne, United Kingdom, NE1 7RU
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