A comparative study of magnetization dynamics in dinuclear dysprosium complexes featuring bridging chloride or trifluoromethanesulfonate ligands

Abstract

We utilized a rigid ligand platform PyCp₂²⁻ (PyCp₂²⁻ = [2,6-(CH₂C₅H₃)₂C₅H₃N]²⁻) to isolate dinuclear Dy³⁺ complexes [(PyCp₂)Dy-(μ-O₂SOCF₃)]₂ (1) and [(PyCp₂)Dy-(μ-Cl)]₂ (3) as well as the mononuclear complex (PyCp₂)Dy(OSO₂CF₃)(thf) (2). Compounds 1 and 2 are the first examples of organometallic Dy³⁺ complexes featuring triflate binding. The isolation of compounds 1 and 3 allows us to comparatively evaluate the effects of the bridging anions on the magnetization dynamics of the dinuclear systems. Our investigations show that although the exchange coupling interactions differ for 1 and 3, the dynamic magnetic properties are dominated by relaxation via the first excited state Kramers doublet of the individual Dy sites. Compounds 1 and 3 exhibit barriers to magnetization reversal (U_eff = 49 cm⁻¹) that can be favorably compared to those of the previously reported examples of [Cp₂Dy(μ-Cl)]₂ (U_eff = 26 cm⁻¹) and [Cp₂Dy(thf)(μ-Cl)]₂ (U_eff = 34 cm⁻¹).