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Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal-metal bond.

Fupin LiuGeorgios VelkosDenis S KrylovLukas SpreeMichal ZaliberaRajyavardhan RayNataliya A SamoylovaChia-Hsiang ChenMarco RosenkranzSandra SchiemenzFrank ZiegsKonstantin NenkovAram KostanyanThomas GreberAnja U B WolterManuel RichterBernd BüchnerStanislav M AvdoshenkoAlexey A Popov
Published in: Nature communications (2019)
Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln2@C80(CH2Ph) dimetallofullerenes (Ln2 = Y2, Gd2, Tb2, Dy2, Ho2, Er2, TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal-metal bonding orbital. Tb2@C80(CH2Ph) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln2@C80(CH2Ph) is redox active, enabling electrochemical tuning of the magnetism.
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