An Inconspicuous Six-Coordinate Neutral Dy^III Single-Ion Magnet with Remarkable Magnetic Anisotropy and Stability

Abstract

It is a crucial challenge to address both magnetic anisotropy and stability for single-molecule magnets (SMMs) used in next-generation nanodevices. Highly axial lanthanide SMMs with neutral charge and moderate coordination numbers represent promising magnetic materials. Here, using iodide ions with large volume and low surface charge density as weak donors, we report a six-coordinate neutral dysprosium SMM [Dy­(Cy3PO)2I3(CH3CN)] with a certain degree of stability exhibiting a huge thermal barrier of 1062 K and hysteresis loops open up to 9 K. Through the elaborate reduction of ligand field strength, an apparent strongly axial crystal field is provided which elicits prominent crystal-field splitting and high axiality with the thermally activated relaxation via the third-excited Kramers’ doublet. Moreover, the profound influence of strong equatorial ligand substitution on the electronic structure and relaxation pathway is clearly explored in DyIII analogues. The result suggests the great potential of the reducing the transverse ligand field in the improvement of SMMs performance.

Octahedral Hexachloro Environment of Dy3+ with Slow Magnetic Relaxation and Luminescent Properties

“…In the excitation spectrum, monitoring the most intense transition at 574 nm, we observe five bands at 350, 363, 385, 451 and 471 nm which can be ascribed to the transitions between the ground state 6 [41] These bands are also in keeping with the absorption spectra (Figure S10).…”

“…In order to have further insight in the magnetic behaviour, we have examined the structures of compounds showing Dy 3 + ions in different octahedral environments (Figure 7 and Table S6) and some characteristic values describing their magnetic behaviours are given in Table 1. [35][36][37][38][39][40][41][42][43] Since the local geometry influences the magnetic properties, we have limited this research to compounds containing Dy 3 + ions surrounded by six ligands in an octahedral geometry (see CShM values in Table 1). As one can observe, the majority of these compounds showing SIM properties tends to exhibit the shorter distances along the axial direction and angle values comprised between 170°and 180°.…”

“…Regarding SIMs, only few examples of mononuclear compounds containing lanthanide ions in octahedral environment were reported. [35][36][37][38][39][40][41][42][43][44][45] Possibility to achieve unusual coordination environments for Ln 3 + ions was observed with the use of Ionic Liquids (ILs). [46] In particular, the formation and stabilization of octahedral entities of formula [LnCl 6 ] 3À in the solid state was described using phosphonium or alkyl imidazolium ILs with Ln chloride salts.…”

Tracking the dissolution–recrystallization structural transformation (DRST) of copper(II) complexes: a combined crystallographic, mass spectrometric and DFT study

“…The Cu II ions in the structures of Cu1 and Cu2 are in different coordination environments, and the angles between the L and SCN À ligands are also different. By using SHAPE, the calculated results suggest that the sixcoordinated Cu II atom is in a twisted octahedral ( = 0.48; is a normalized measure of pyramidalization) geometry formed by the coordinated atoms N 4 O 2 for Cu1 (Li et al, 2020) and every five-coordinated Cu II atom is in a quadrangular ( = 0.39) pyramidal geometry formed by the coordinated atoms N 2 O 3 for Cu2 (Tables S3 and S4 in the supporting information) (Li et al, 2020;Alvarez et al, 2005). The twisted octahedral geometry of Cu II in Cu1 is caused by Jahn-Teller distortion.…”

Insights into D4h@metal-symmetry single-molecule magnetism: the case of a dysprosium-bis(boryloxide) complex

“…Around twenty (pseudo) O h and D 4h @Dy-SMM complexes are known, but few exhibit U eff values 4700 K: notable examples include [Dy(BIPM) 2 ] À (721/813 K), 12 [Dy{NC(NArCH) 2 }(Cl) 2 (THF) 3 ] (803 K, Ar = 2,6-Pr i 2 C 6 H 3 ), 13 [Dy(Cy 3 PO) 2 (I) 3 (CH 3 CN)] (1062 K), 14 [Dy(DiMeQ) 2 (Cl) 3 (H 2 O)] (1100 K), 15 and recently [Dy(OBu t ) 2 (Py-4-R) 4 ] + (1810-2075 K, R = Ph, N(CH 2 CH 2 ) 2 CH 2 , N(CH 2 CH 2 ) 2 ). 16 For D 4h @Dy(III) SMMs, the latter three bis(alkoxide) complexes exhibit remarkable U eff values, yet conversely D 4h @Dy(III) [Dy(carbazolyl) 2 (L) 4 ] + (L = py, THF) exhibit U eff barriers of 57-72 K. 17 This is surprising because electrostatic models predict that [Dy(X) 2 (THF) 4 ] + (X = monoanionic ligand) species should exhibit U eff values of B860-1500 K. 5 The experimental D 4h @Dy(III) U eff variance of B2000 K suggests that much remains to be understood in electrostatic models, and so further data are required to validate or modify electrostatic potential theory.…”