Rae, Annabel and Byrne, Keelan M. and Brown, Scott A. and Kennedy, Alan R. and Krämer, Tobias and Mulvey, Robert E. and Robertson, Stuart D. (2022) Sigma/pi Bonding Preferences of Solvated Alkali‐Metal Cations to Ditopic Arylmethyl Anions. Chemistry – A European Journal, 28 (18). pp. 1-17. ISSN 0947-6539

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Abstract

Arylmethyl anions allow alkali-metals to bind in a σ-fashion to the lateral carbanionic centre or a π-fashion to the aryl ring or in between these extremities, with the trend towards π bonding increasing on descending group 1. Here we review known alkali metal structures of diphenylmethane, fluorene, 2-benzylpyridine and 4-benzylpyridine. Next, we synthesise Li, Na, K monomers of these diarylmethyls using polydentate donors PMDETA or Me6TREN to remove competing oligomerizing interactions, studying the effect that two aromatic rings has on negative charge (de)localisation via NMR, X-ray crystallographic and DFT studies. Diphenylmethyl and fluorenyl anions maintain C(H)−M interactions regardless of alkali-metal, although the adjacent arene carbons engage in interactions with larger alkali-metals. Introducing a nitrogen atom into the ring (at the 2- or 4-position) encourages relocalisation of negative charge away from the deprotonated carbon and onto nitrogen. Phenyl(2-pyridyl)methyl moves from an enamide formation at one extremity (lithium) to an aza-allyl formation at the other extremity (potassium), while C- or N-coordination modes become energetically viable for Na and K phenyl(4-pyridyl)methyl complexes.

Item Type:	Article
Keywords:	Sigma; pi; Bonding; Preferences; Solvated; Alkali‐Metal; Cations; Ditopic Arylmethyl Anions;
Academic Unit:	Faculty of Science and Engineering > Chemistry Faculty of Science and Engineering > Research Institutes > Hamilton Institute
Item ID:	18518
Identification Number:	https://doi.org/10.1002/chem.202104260
Depositing User:	Tobias Kraemer
Date Deposited:	15 May 2024 10:28
Journal or Publication Title:	Chemistry – A European Journal
Publisher:	Wiley
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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