Synthesis and Single-Molecule Magnetic Properties of Dinuclear Dysprosium Phenylchalcogeno Guanidinate Complexes from Dysprosium Inverse-Sandwich Arene Complexes with Diphenyl Dichalcogenides

Abstract

Recent years have witnessed a surge in the synthesis of rare-earth inverse-sandwich arene complexes, driven by their ability to serve as reductants or low-valent rare-earth metal synthons. In this work, we utilized two room-temperature stable inverse-sandwich dysprosium arene complexes, [(L2Dy)2Ar] (L = [(Me3Si)2NC(NiPr)2], Ar = μ-η6:η6-C6H6 (A) and μ-η6:η6-C7H8 (B)), to react with diphenyl dichalcogenides to afford a series of dinuclear dysprosium di-μ-phenylchalcogeno complexes [{L2Dy(μ-EPh)}2] (E = S (1), Se (2) and Te (3)). Magnetic studies on these complexes revealed that all three compounds are single-molecule magnets (SMMs), exhibiting slow magnetic relaxation governed predominantly by the Raman relaxation mechanism. Ab initio calculations indicate that the chalcogen atoms occupy equatorial coordination sites around the Dy(III) ions; consequently, the energy splitting of the low-lying Kramers doublets increases with the atomic radius of the chalcogen (S < Se < Te), leading to a progressive increase in the temperature where magnetic relaxation becomes observable for complexes 1–3. These findings suggest that rare-earth inverse-sandwich arene complexes can be effectively adopted as reductants. This approach provides an alternative way for the design of rare-earth SMMs with magnetic exchange coupling between paramagnetic centers.