Magnetic ionic plastic crystal: choline[FeCl4]

Abstract

A novel organic ionic plastic crystal (OIPC) based on a quaternary ammonium cation and a tetrachloroferrate anion has been synthesized with the intention of combining the properties of the ionic plastic crystal and the magnetism originating from the iron incorporated in the anion. The thermal analysis of the obtained OIPC showed a solid-solid phase transition below room temperature and a high melting point above 220 °C, indicating their plastic crystalline behaviour over a wide temperature range, as well as thermal stability up to approximately 200 °C. The magnetization measurements show the presence of three-dimensional antiferromagnetic ordering below 4 K. The results from electrochemical characterization display a solid-state ionic conduction sufficiently high and stable (between 10(-2.7) and 10(-3.6) S cm(-1) from 20 to 180 °C) for electrochemical applications.

A Multifunctional Magnetic Material under Pressure

“…The neutron data are also in good agreement with this value of T N since the intensity of the magnetic reflections decreases with temperature, vanishing between 2.3 and 2.45 K. The refined value of the magnetic moment correspondingly decreases (Figure 4), showing a temperature dependence that approximately follows a power‐law Ct β corresponding to a Heisenberg 3D ordering of S =5/2 spins (with C =5, t =| T − T N |, T N =2.4 K, and β =0.364),22 as is expected for Fe III ions. A 3D antiferromagnetic order in the same temperature range has indeed recently been reported in the plastic crystal choline[FeCl 4 ],23 although the absence of structural data impedes magneto‐structural correlation in this case. The magnetic order in 1 finds its origin in two types of interactions among these Fe III S =5/2 spins.…”

“…Indeed, both the ferromagnetic exchange interaction within the FeBr 4 − ions along c and the antiferromagnetic dipolar interaction between these stacks in the ab plane are expected to increase with reduced Fe III ⋅⋅⋅Fe III distances 21. 23 The effect of the former should however be dominant since the corresponding Fe III ⋅⋅⋅Fe III distances along the c axis suffer a stronger reduction under pressure than those distances contained in the ab plane (−7.7 % vs. −5.6 %, Table 2), and the exchange interaction is much more sensitive to distance variations (ca. r −10 ) than the dipolar interaction (ca.…”

Crystal Structures and Phase Sequences of Metallocenium Salts with Fluorinated Anions: Effects of Molecular Size and Symmetry on Phase Transitions to Ionic Plastic Crystals

“…The space groups are also showni nt he charts,o f which those indicated by an asterisk were taken from the literature. [16] These materials may lead to novel electromagnetic phenomena. [7] tice constant of 13.00 .T he interionicd istance is 6.50 , which is in agreement with the sum of the ionic radii estimated by DFT calculations (6.95 ).…”

“…Recently,a ne xample of ap aramagnetic ionic plastic crystal, [choline][FeCl 4 ], hasb een reported. [16] These materials may lead to novel electromagnetic phenomena.…”

A Magnetic Ionic Liquid Based on Tetrachloroferrate Exhibits Three‐Dimensional Magnetic Ordering: A Combined Experimental and Theoretical Study of the Magnetic Interaction Mechanism

“…This value corresponds to an effective paramagnetic moment (m eff ) of 5.88 m B per Fe ion; this agrees with the expected value of 4.375 emuK mol À1 Oe À1 (5.92 m B ) for an Fe 3 + ion with a magnetic spin S = 5/2. [25] Due to the anisotropy of the crystal, a combination of a modified expression of the one-dimensional Bonner and Fisher model, [26] for the interplane interactions, and a two-dimensional Rushbrook and Wood model, [27] for the intraplane interactions, was used to extract the magnetic exchange couplings between the Fe 3 + ions (see magnetic fitting calculations in the Supporting Information). The best fit leads to the parameters J ?…”