[ReF6]2−: A Robust Module for the Design of Molecule-Based Magnetic Materials

• Published in: Angewandte Chemie Vol. 126; no. 5; pp. 1375 - 1378
• Main Authors: Pedersen, Kasper S., Sigrist, Marc, Sørensen, Mikkel A., Barra, Anne-Laure, Weyhermüller, Thomas, Piligkos, Stergios, Thuesen, Christian Aa, Vinum, Morten G., Mutka, Hannu, Weihe, Høgni, Clérac, Rodolphe, Bendix, Jesper
• Format: Journal Article
• Language: English; German
• Published: Weinheim WILEY-VCH Verlag 27-01-2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Chemistry; Einzelmolekülmagnete; Fluorid; Koordinationspolymere; Magnetische Anisotropie; Magnetism; R&D; Research & development; Rhenium
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201309981

A facile synthesis of the [ReF6]2− ion and its use as a building block to synthesize magnetic systems are reported. Using dc and ac magnetic susceptibility measurements, INS and EPR spectroscopies, the magnetic properties of the isolated [ReF6]2− unit in (PPh4)2[ReF6]⋅2 H2O (1) have been fully studied including the slow relaxation of the magnetization observed below ca. 4 K. This slow dynamic is preserved for the one‐dimensional coordination polymer [Zn(viz)4(ReF6)]∞ (2, viz=1‐vinylimidazole), demonstrating the irrelevance of low symmetry for such magnetization dynamics in systems with easy‐plane‐type anisotropy. The ability of fluoride to mediate significant exchange interactions is exemplified by the isostructural [Ni(viz)4(ReF6)]∞ (3) analogue in which the ferromagnetic NiII–ReIV interaction (+10.8 cm−1) dwarfs the coupling present in related cyanide‐bridged systems. These results reveal [ReF6]2− to be an unique new module for the design of molecule‐based magnetic materials.
Eine axiale Störung verleiht dem oktaedrischen Ion [ReF6]2− eine starke magnetische Anisotropie und eine langsame Relaxation der Magnetisierung. Das robuste [ReF6]2− kann als strukturdirigierender magnetischer Baustein in ausgedehnten Systemen eingesetzt werden, z. B. in den eindimensionalen Koordinationspolymeren [M(viz)4(ReF6)]∞ (viz=1‐Vinylimidazol; M=Zn, Ni), die ausgeprägte magnetische Wechselwirkungen über die Fluoridbrücken aufweisen.