Molecular Organo-Dysprosium Polychalcogenides Isolated from Inverse-Sandwich Dysprosium Arene Complexes with Chalcogens

Abstract In recent years, there has been intensive interest in synthesizing and characterizing rare earth inverse-sandwich arene complexes due to their intriguing structural and electronic properties, and they can be exploited as low-valent synthons similar to divalent rare earth compounds. Herein, we use two room-temperature stable, previously reported inverse-sandwich dysprosium arene complexes [(L2Dy)2Ar] (L = [(Me3Si)2NC(NiPr)2], Ar = μ-η:6η6-C6H6 (A) and μ-η:6η6-C7H8 (B)) to react with elemental sulfur, selenium, and tellurium to isolate a series of dysprosium polychalcogenides, namely, [{LDy(μ2-η3-S4)}3] (1), [(L2Dy)2(μ2-η3-S3)] (2), [(L2Dy)2(μ2-η2-Se2)0.6/(μ2-η3-Se3)0.4] (3), and cocrystalline 3 containing two components: 60% [(L2Dy)2(μ2-η2-Se2)] (3a) and 40% [(L2Dy)2(μ2-η3-Se3)] (3b) and [(L2Dy)2(μ2-η2-Te2)] (4). Magnetic studies on these Dy polychalcogenide compounds reveal that 2 and 4 are single-molecule magnets with slow relaxation of magnetization dominated by quantum tunneling at low temperature. CASSCF-SO calculations support and interpret the experimental energy barriers for 2 and 4. These findings suggest thermally stable nonclassical rare earth inverse-sandwich arene complexes can be adopted as reductants to access new types of rare earth molecules with rich structural diversities and potential applications.