Radical‐Bridged Heterometallic Single‐Molecule Magnets Incorporating Four Lanthanoceniums

Abstract

AbstractThe syntheses and magnetic properties of organometallic heterometallic compounds [K(THF)6]{CoI[(μ3‐HAN)RE2Cp*4]2} (1‐RE) and [K(Crypt)]2{CoI[(μ3‐HAN)RE2Cp*4]2} (2‐RE) containing hexaazatrinaphthylene radicals (HAN⋅3−) and four rare earth (RE) ions are reported. 1‐RE shows isolable species with ligand‐based mixed valency as revealed by cyclic voltammetry (CV) thus leading to the isolation of 2‐RE via one‐electron chemical reduction. Strong electronic communication in mixed‐valency supports stronger overall ferromagnetic behaviors in 2‐RE than 1‐RE containing Gd and Dy ions. Ac magnetic susceptibility data reveal 1‐Dy and 2‐Dy both exhibit slow magnetic relaxation. Importantly, larger coercive field was observed in the hysteresis of 2‐Dy at 2.0 K, indicating the enhanced SMM behavior compared with 1‐Dy. Ligand‐based mixed‐valency strategy has been used for the first time to improve the magnetic coupling in lanthanide (Ln) SMMs, thus opening up new ways to construct strongly coupled Ln‐SMMs.