Formation of the layered conductive magnet CrCl2(pyrazine)2 through redox-active coordination chemistry

• Published in: Nature chemistry 2018-10, Vol.10 (10), p.1056-1061
• Main Authors: Pedersen, Kasper S., Perlepe, Panagiota, Aubrey, Michael L., Woodruff, Daniel N., Reyes-Lillo, Sebastian E., Reinholdt, Anders, Voigt, Laura, Li, Zheshen, Borup, Kasper, Rouzières, Mathieu, Samohvalov, Dumitru, Wilhelm, Fabrice, Rogalev, Andrei, Neaton, Jeffrey B., Long, Jeffrey R., Clérac, Rodolphe
• Format: Article
• Language: English
• Subjects: 639/638/263; 639/638/298; 639/638/298/917; 639/638/298/920; 639/638/911; Analytical Chemistry; Biochemistry; Chemical Sciences; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Chromium; Conductors; Coordination compounds; Electrical conductivity; Electrical resistivity; Ferrimagnetism; Galling; Inorganic Chemistry; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ligands; Magnetic properties; Magnets; Material chemistry; Metal ions; Organic Chemistry; Physical Chemistry; Pyrazine; Spintronics
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/s41557-018-0107-7

The unique properties of graphene, transition-metal dichalcogenides and other two-dimensional (2D) materials have boosted interest in layered coordination solids. In particular, 2D materials that behave as both conductors and magnets could find applications in quantum magnetoelectronics and spintronics. Here, we report the synthesis of CrCl 2 (pyrazine) 2 , an air-stable layered solid, by reaction of CrCl 2 with pyrazine (pyz). This compound displays a ferrimagnetic order below ∼55 K, reflecting the presence of strong magnetic interactions. Electrical conductivity measurements demonstrate that CrCl 2 (pyz) 2 reaches a conductivity of 32 mS cm –1 at room temperature, which operates through a 2D hopping-based transport mechanism. These properties are induced by the redox-activity of the pyrazine ligand, which leads to a smearing of the Cr 3 d and pyrazine π states. We suggest that the combination of redox-active ligands and reducing paramagnetic metal ions represents a general approach towards tuneable 2D materials that consist of charge-neutral layers and exhibit both long-range magnetic order and high electronic conductivity. Layered coordination polymers are attractive for the preparation of advanced 2D materials but they are typically non-magnetic insulators. Now such a layered network, CrCl 2 (pyrazine) 2 , has been prepared that comprises a paramagnetic metal ion and a redox-active ligand. The material exhibits both magnetism — with a ferrimagnetic ground state — and high electrical conductivity.