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; Kays, Deborah L.

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.

Citation

Valentine, A. J., Geer, A. M., Taylor, L. J., Teale, A. M., Wood, K. E., Williams, H. E. L., Lewis, W., Argent, S. P., McMaster, J., & Kays, D. L. (2021). Structural and electronic studies of substituted m-terphenyl lithium complexes. Dalton Transactions, 50(2), 722-728. https://doi.org/10.1039/d0dt03972a

• Journal Article Type: Article
• Acceptance Date: Dec 3, 2020
• Online Publication Date: Dec 8, 2020
• Publication Date: Jan 14, 2021
• Deposit Date: Feb 18, 2021
• Publicly Available Date: Feb 18, 2021
• Journal: Dalton Transactions
• Print ISSN: 1477-9226
• Electronic ISSN: 1477-9234
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 50
• Issue: 2
• Pages: 722-728
• DOI: https://doi.org/10.1039/d0dt03972a
• Keywords: Inorganic Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/5173154
• Publisher URL: https://pubs.rsc.org/en/content/articlelanding/2021/DT/D0DT03972A
• Additional Information: : This document is Similarity Check deposited; : Supplementary Information; : Crystal Structure Data; : Andrew J. Valentine (ORCID); : Andrew J. Valentine (ResearcherID); : Ana M. Geer (ORCID); : Laurence J. Taylor (ORCID); : Andrew M. Teale (ORCID); : Huw E. L. Williams (ORCID); : William Lewis (ORCID); : William Lewis (ResearcherID); : Stephen P. Argent (ORCID); : Stephen P. Argent (ResearcherID); : Jonathan McMaster (ORCID); : Jonathan McMaster (ResearcherID); : Deborah L. Kays (ORCID); : Deborah L. Kays (ResearcherID); : Single-blind; : Received 19 November 2020; Accepted 3 December 2020; Accepted Manuscript published 8 December 2020; Advance Article published 21 December 2020