A fluorobenzene-bound dysprosium half-sandwich dication single-molecule magnet

Sophie Corner, William Blackmore, Gemma Gransbury, Andrea Mattioni, George Whitehead, Nicholas F. Chiltona, David Mills*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Dysprosium single-molecule magnets (SMMs) with two mutually trans- anionic ligands have shown large crystal field (CF) splitting, giving record effective energy barriers to magnetic reversal (Ueff) and hysteresis temperatures (TH). However, these complexes tend to be bent, imposing a transverse field that reduces the purity of the mJ projections of the CF states and promotes magnetic relaxation. A complex with only one charge-dense anionic ligand could have more pure CF states, and thus high Ueff and TH. Here we report an SMM with this topology, a half-sandwich Dy(III) complex [Dy(Cp*)(FPh)6][{Al[OC(CF3)3]3}2(μ-F)]2 (1-Dy; Cp* = C5Me5), and its Y(III) analogue 1-Y; 1-Dy exhibits Ueff = 545(30) cm–1 and TH = 14 K at sweep rates of 22 Oe s–1. The Cp* ligand imposes a strong axial CF, which is assisted by one axial fluorobenzene; the five equatorially-bound neutral fluorobenzenes present only weak transverse interactions to give a pseudo-pentagonal bipyramidal geometry. The salt metathesis reaction of 1-Y with KCpʹʹʹ (Cpʹʹʹ = {C5H2(SiMe3)3-1,2,4}) gave the sandwich complex [Y(Cpʹʹʹ)(Cp*)(FPh)2][{Al[OC(CF3)3]3}2(μ-F)] (4-Y), showing that the fluorobenzenes of 1-Y are easily displaced. We envisage that these methodologies could be adapted in future to prepare high-performance axial Dy SMMs with ligands that are more sterically demanding than Cp*.
Original languageEnglish
JournalChemical Science
Early online date4 Dec 2024
DOIs
Publication statusPublished - 1 Jan 2025

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