Structural and electronic studies of substituted m-terphenyl lithium complexes

Valentine, Andrew J., Geer, Ana M., Taylor, Laurence J., Teale, Andrew M., Wood, Katherine E., Williams, Huw E. L., Lewis, William, Argent, Stephen P., McMaster, Jonathan and Kays, Deborah L. ORCID: https://orcid.org/0000-0002-4616-6001 2021. Structural and electronic studies of substituted m-terphenyl lithium complexes. Dalton Transactions 50 (2) , pp. 722-728. 10.1039/D0DT03972A

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Abstract

The effect of para-substitution upon the structural and electronic properties of a series of m-terphenyl lithium complexes [R–Ar#–Li]2 (R = t-Bu 1, SiMe32, H 3, Cl 4, CF35; where R–Ar# = 2,6-{2,6-Xyl}2-4-R-C6H2 and 2,6-Xyl = 2,6-Me2C6H3) has been investigated. X-ray crystallography reveals the complexes to be structurally similar, with little variation in C–M–C bond lengths and angles across the series. However, in-depth NMR spectroscopic studies reveal notable electronic differences, showing a linear correlation between the 7Li{1H} NMR chemical shifts of the para-substituted complexes and their Hammett constants. The flanking methyl protons exhibit a similar electronic shift in the 1H NMR spectra, which has been rationalised by the presence of through-space Li⋯H interactions, as evidenced by two-dimensional 7Li–1H heteronuclear Overhauser spectroscopy (HOESY). In both cases, electron-withdrawing substituents are found to cause an upfield peak shift. A computational analysis is employed to account for these trends.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	Royal Society of Chemistry
ISSN:	1477-9226
Date of First Compliant Deposit:	7 August 2024
Date of Acceptance:	3 December 2020
Last Modified:	07 Aug 2024 09:03
URI:	https://orca.cardiff.ac.uk/id/eprint/170343

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