Issue 4, 2015

Dynamical effects on the magnetic properties of dithiazolyl bistable materials

Abstract

The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study (usually an X-ray crystal structure). Here, by means of a computational study, we compare the results obtained using such a static approach with those obtained by explicitly accounting for thermal fluctuations, and uncover the serious limitations of the static perspective when dealing with magnetic crystals whose radicals undergo wide-amplitude motions. As a proof of concept, these limitations are illustrated for the magnetically bistable 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) material. For its high-temperature phase at 300 K, we show that nuclear dynamics induce large fluctuations in the magnetic exchange interactions (JAB) between spins (up to 1000% of the average value). These deviations result in a ∼20% difference between the 300 K magnetic susceptibility computed by explicitly considering the nuclear dynamics and that computed using the X-ray structure, the former being in better agreement with the experimental data. The unveiled strong coupling between JAB interactions and intermolecular vibrations reveals that considering JAB as a constant value at a given temperature (as always done in molecular magnetism) leads to a flawed description of the magnetism of TTTA. Instead, the physically relevant concept in this case is the statistical distribution of JAB values. The discovery that a single X-ray structure is not adequate enough to interpret the magnetic properties of TTTA is also expected to be decisive in other organic magnets with dominant exchange interactions propagating through labile π–π networks.

Graphical abstract: Dynamical effects on the magnetic properties of dithiazolyl bistable materials

Supplementary files

Article information

Article type
Edge Article
Submitted
18 Dec 2014
Accepted
22 Jan 2015
First published
23 Jan 2015
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2015,6, 2371-2381

Dynamical effects on the magnetic properties of dithiazolyl bistable materials

S. Vela, M. Deumal, M. Shiga, J. J. Novoa and J. Ribas-Arino, Chem. Sci., 2015, 6, 2371 DOI: 10.1039/C4SC03930K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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