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A Bis-Monophospholyl Dysprosium Cation Showing Magnetic Hysteresis at 48 Kelvin

preprint
submitted on 25.10.2019 and posted on 29.10.2019 by Peter Evans, Daniel Reta, George F. S. Whitehead, Nicholas Chilton, David Mills
Single-molecule magnets (SMMs) have potential applications in high-density data storage, but magnetic relaxation times at elevated temperatures must be increased to make them practically useful. Bis-cyclopentadienyl lanthanide sandwich complexes have emerged as the leading candidates for SMMs that show magnetic memory at liquid nitrogen temperatures, but the relaxation mechanisms mediated by aromatic C5 rings have not been fully established. Here we synthesise a bis-monophospholyl dysprosium SMM [Dy(Dtp)2][Al{OC(CF3)3}4] (1, Dtp = {P(CtBuCMe)2}) by the treatment of in situ-prepared “[Dy(Dtp)2(C3H5)]” with [HNEt3][Al{OC(CF3)3}4]. SQUID magnetometry reveals that 1 has an effective barrier to magnetisation reversal of 1,760 K (1,223 cm–1) and magnetic hysteresis up to 48 K. Ab initio calculation of the spin dynamics reveal that transitions out of the ground state are slower in 1 than in the first reported dysprosocenium SMM, [Dy(Cpttt)2][B(C6F5)4] (Cpttt = C5H2tBu3-1,2,4), however relaxation is faster in 1 overall due to the compression of electronic energies and to vibrational modes being brought on-resonance by the chemical and structural changes introduced by the bis-Dtp framework. With the preparation and analysis of 1 we are thus able to further refine our understanding of relaxation processes operating in bis-C5/C4P sandwich lanthanide SMMs, which is the necessary first step towards rationally achieving higher magnetic blocking temperatures in these systems in future.

Funding

EPSRC EP/R002605X/1, EP/P002560/1 and EP/K039547/1

Royal Society University Research Fellowship

History

Email Address of Submitting Author

david.mills@manchester.ac.uk

Institution

The University of Manchester

Country

United Kingdom

ORCID For Submitting Author

0000-0003-1575-7754

Declaration of Conflict of Interest

No conflict of interest

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