Studies of the Temperature Dependence of the Structure and Magnetism of a Hexagonal-Bipyramidal Dysprosium(III) Single-Molecule Magnet

You-Song Ding; William J A Blackmore; Yuan-Qi Zhai; Marcus J Giansiracusa; Daniel Reta; Inigo Vitorica-Yrezabal; Richard E P Winpenny; Nicholas F Chilton; Yan-Zhen Zheng

doi:10.1021/acs.inorgchem.1c02779

Studies of the Temperature Dependence of the Structure and Magnetism of a Hexagonal-Bipyramidal Dysprosium(III) Single-Molecule Magnet

Inorg Chem. 2022 Jan 10;61(1):227-235. doi: 10.1021/acs.inorgchem.1c02779. Epub 2021 Dec 23.

Affiliations

¹ Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Key Laboratory of Sustainable Energy and Materials Chemistry, School of Chemistry, and School of Physics, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
² Department of Chemistry, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
³ Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.

Abstract

The hexagonal-bipyramidal lanthanide(III) complex [Dy(O^tBu)Cl(18-C-6)][BPh₄] (1; 18-C-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane ether) displays an energy barrier for magnetization reversal (U_eff) of ca. 1000 K in a zero direct-current field. Temperature-dependent X-ray diffraction studies of 1 down to 30 K reveal bending of the Cl-Ln-O^tBu angle at low temperature. Using ab initio calculations, we show that significant bending of the O-Dy-Cl angle upon cooling from 273 to 100 K leads to a ca. 10% decrease in the energy of the excited electronic states. A thorough exploration of the temperature and field dependencies of the magnetic relaxation rate reveals that magnetic relaxation is dictated by five mechanisms in different regimes: Orbach, Raman-I, quantum tunnelling of magnetization, and Raman-II, in addition to the observation of a phonon bottleneck effect.