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Abstract
The seven-membered cyclic potassium alumanyl species, [{SiN Mes}AlK] 2 [{SiN Mes}={CH 2SiMe 2N(Mes)} 2; Mes=2,4,6-Me 3C 6H 2], which adopts a dimeric structure supported by flanking K-aryl interactions, has been isolated either by direct reduction of the iodide precursor, [{SiN Mes}AlI], or in a stepwise manner via the intermediate dialumane, [{SiN Mes}Al] 2. Although the intermediate dialumane has not been observed by reduction of a Dipp-substituted analogue (Dipp=2,6-i-Pr 2C 6H 3), partial oxidation of the potassium alumanyl species, [{SiN Dipp}AlK] 2, where {SiN Dipp}={CH 2SiMe 2N(Dipp)} 2, provided the extremely encumbered dialumane [{SiN Dipp}Al] 2. [{SiN Dipp}AlK] 2 reacts with toluene by reductive activation of a methyl C(sp 3)-H bond to provide the benzyl hydridoaluminate, [{SiN Dipp}AlH(CH 2Ph)]K, and as a nucleophile with BPh 3 and RN=C=NR (R=i-Pr, Cy) to yield the respective Al-B- and Al-C-bonded potassium aluminaborate and alumina-amidinate products. The dimeric structure of [{SiN Dipp}AlK] 2 can be disrupted by partial or complete sequestration of potassium. Equimolar reactions with 18-crown-6 result in the corresponding monomeric potassium alumanyl, [{SiN Dipp}Al−K(18-cr-6)], which provides a rare example of a direct Al−K contact. In contrast, complete encapsulation of the potassium cation of [{SiN Dipp}AlK] 2, either by an excess of 18-cr-6 or 2,2,2-cryptand, allows the respective isolation of bright orange charge-separated species comprising the ‘free’ [{SiN Dipp}Al] − alumanyl anion. Density functional theory (DFT) calculations performed on this moiety indicate HOMO-LUMO energy gaps in the of order 200–250 kJ mol −1.
Original language | English |
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Pages (from-to) | 14971-14980 |
Number of pages | 10 |
Journal | Chemistry - A European Journal |
Volume | 27 |
Issue number | 60 |
Early online date | 21 Sept 2021 |
DOIs | |
Publication status | Published - 25 Oct 2021 |
Bibliographical note
Funding Information:We thank the Royal Commission for the Exhibition of 1851 for the provision of a Postdoctoral Fellowship (RJS) and the EPSRC (EP/R020752/1) for support of this research. This research made use of the Balena High Performance Computing (HPC) Service at the University of Bath.
Keywords
- aluminium
- coordination modes
- main group chemistry
- metal-metal interactions
ASJC Scopus subject areas
- Catalysis
- Organic Chemistry
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Dive into the research topics of 'Seven-membered Cyclic Potassium Diamidoalumanyls'. Together they form a unique fingerprint.Projects
- 2 Finished
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Ryan Schwamm- 1851 Fellowship - Activation of Nitrogen using Alkaline Earth Metals
Schwamm, R. (PI) & Hill, M. (CoI)
Royal Commission for the Exhibition of 1851
5/11/18 → 4/11/21
Project: UK charity
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Nucleophilic alkaline earth boryls: from conception and theory to application
Hill, M. (PI), Cresswell, A. (CoI) & McMullin, C. (Researcher)
Engineering and Physical Sciences Research Council
1/05/18 → 31/07/22
Project: Research council