Slow magnetic relaxation in Fe(ii) m-terphenyl complexes

Valentine, Andrew J.; Geer, Ana M.; Blundell, Toby J.; Tovey, Will; Cliffe, Matthew J.; Davies, E. Stephen; Argent, Stephen P.; Lewis, William; McMaster, Jonathan; Taylor, Laurence J.; Reta, Daniel; Kays, Deborah L.

Abstract

Two-coordinate transition metal complexes are exciting candidates for single-molecule magnets (SMMs) because their highly axial coordination environments lead to sizeable magnetic anisotropy. We report a series of five structurally related two-coordinate Fe(II) m-terphenyl complexes (4-R-2,6-Xyl2C6H2)2Fe [R = tBu (1), SiMe3 (2), H (3), Cl (4), CF3 (5)] where, by changing the functionalisation of the para-substituent (R), we alter their magnetic function. All five complexes are field-induced single-molecule magnets, with relaxation rates that are well-described by a combination of direct and Raman mechanisms. By using more electron donating R groups we were able to slow the rate of magnetic relaxation. Our ab initio calculations predict a large crystal field splitting (>850 cm−1) and sizeable zero-field splitting parameters (ca. −60 cm−1, |E| < 0.2 cm−1) for 1–5. These favourable magnetic properties suggest that m-terphenyl ligands have untapped potential as chemically versatile ligands able to impose highly axial crystal fields.

Citation

Valentine, A. J., Geer, A. M., Blundell, T. J., Tovey, W., Cliffe, M. J., Davies, E. S., …Kays, D. L. (2022). Slow magnetic relaxation in Fe(ii) m-terphenyl complexes. Dalton Transactions, 51(47), 18118-18126. https://doi.org/10.1039/d2dt03531f

• Journal Article Type: Article
• Acceptance Date: Nov 7, 2022
• Online Publication Date: Nov 8, 2022
• Publication Date: 2022
• Deposit Date: Feb 20, 2023
• Publicly Available Date: Feb 20, 2023
• Journal: Dalton Transactions
• Print ISSN: 1477-9226
• Electronic ISSN: 1477-9234
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 51
• Issue: 47
• Pages: 18118-18126
• DOI: https://doi.org/10.1039/d2dt03531f