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

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 [(L 2 Dy) 2 Ar] (L = [(Me 3 Si) 2 NC(N i Pr) 2 ], Ar = μ-η: 6 η 6 -C 6 H 6 ( A ) and μ-η: 6 η 6 -C 7 H 8 ( B )) to react with elemental sulfur, selenium, and tellurium to isolate a series of dysprosium polychalcogenides, namely, [{LDy(μ 2 -η 3 -S 4 )} 3 ] ( 1 ), [(L 2 Dy) 2 (μ 2 -η 3 -S 3 )] ( 2 ), [(L 2 Dy) 2 (μ 2 -η 2 -Se 2 ) 0.6 /(μ 2 -η 3 -Se 3 ) 0.4 ] ( 3 ), and cocrystalline 3 containing two components: 60% [(L 2 Dy) 2 (μ 2 -η 2 -Se 2 )] ( 3a ) and 40% [(L 2 Dy) 2 (μ 2 -η 3 -Se 3 )] ( 3b ) and [(L 2 Dy) 2 (μ 2 -η 2 -Te 2 )] ( 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.