Parmar, Vijay S.Ortu, FabrizioMa, XiaozhouChilton, Nicholas F.Clérac, RodolpheMills, David P.Winpenny, Richard E. P.2025-06-112025-06-110947-6539Bibtex:parmar_probing_2020https://hdl.handle.net/1885/733758125A new family of five-coordinate lanthanide single-molecule magnets (Ln SMMs) [Dy(Mes*O)2(THF)2X] (Mes*=2,4,6-tri-tert-butylphenyl; X=Cl, 1; Br, 2; I, 3) is reported with energy barriers to magnetic reversal >1200 K. The five-coordinate DyIII ions have distorted square pyramidal geometries, with halide anions on the apex, and two Mes*O ligands mutually trans- to each other, and the two THF molecules forming the second trans- pair. These geometrical features lead to a large magnetic anisotropy in these complexes along the trans-Mes*O direction. QTM and Raman relaxation times are enhanced by varying the apex halide from Cl to Br to I, or by dilution in a diamagnetic yttrium analogue.V.P. thanks the University of Manchester for the President's Doctoral Scholarship. D.P.M. thanks the EPSRC (UK) for support (EP/P002560/1) and funding of a diffractometer (EP/P001386/1) and SQUID magnetometer. R.C. and X.M. thank the University of Bordeaux, the ANR, the CNRS, the Region Nouvelle Aquitaine, the MOLSPIN COST action CA15128, the GdR MCM‐2: Magnétisme et Commutation Moléculaires and the Chinese Scholarship Council (CSC) for the PhD funding of X.M. R.E.P.W. thanks the ERC for an Advanced Grant (ERC‐2017‐ADG‐786734) and EPSRC UK for an Established Career Fellowship (EP/R011079/1). N.F.C. thanks The Royal Society for a Research Fellowship. We acknowledge the University of Manchester for access to the Computational Shared Facility. Research data files supporting this publication are available from Mendeley Data at DOI:10.17632/jzgm7zjx7h.1.5enmagnetic anisotropylanthanidessingle-molecule magnetsaryloxidesparamagnetic relaxation2020-03-2610.1002/chem.20200123585085689907