Synthesis, Structure, and Magnetic Properties of Rare-Earth Benzoborole Complexes

The first examples of benzoborole rare-earth ate complexes [BoRE(COT)][Li(DME)3] (3RE; Bo = benzoborole dianion; COT = cyclooctatetraene; RE = Y, Dy, Er; DME = 1,2-dimethoxyethane) with a sandwich structure have been synthesized by the reaction of a benzoborole dianion with RECl3 followed by treatment with cyclooctatetraene dipotassium salt. These complexes have been fully characterized by X-ray diffraction analysis and IR, UV–vis, and NMR spectroscopy. Remarkably, the Dy and Er complexes exhibit single-molecule-magnet behaviors with effective energy barriers (Ueff) of 98 cm–1 (141 K) and 109 cm–1 (157 K), respectively, and their magnetic hysteresis loops were observed at 2 K.