Weak exchange coupling effects leading to fast magnetic relaxations in a trinuclear dysprosium single-molecule magnet

Abstract

Investigating the magnetic anisotropy and magnetic interactions of lanthanide complexes is of vital importance for an in-depth understanding of their magnetic properties. Herein, we reported the synthetic, structural and magnetic studies of a triangular type dysprosium complex (1Dy₃, [{(Cp)(Tp*)Ln(μ-bta)}₃·2(thf)], Cp = C₅H₅, Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate anion, btaH = 1H-1,2,3-benzotriazole). 2Dy ([(Cp)Dy(Tp)₂·C₇H₈], Tp = hydrotris(1-pyrazolyl)borate) was investigated by single-crystal angular-resolved susceptibility measurements and computational studies to help understand the magnetic anisotropy of 1Dy₃. The easy axis of three Dy^III ions in 1Dy₃ was orientated out of the triangular dysprosium plane. The exchange interactions were small (−0.85 cm⁻¹) but caused remarkable effects on magnetic relaxations at low temperature. In the temperature range from 2 K to 4 K, magnetic relaxation occurred via the exchange-coupled low-lying excited states, inhibiting magnetic hysteresis. Our study showed that weak intramolecular magnetic interactions can significantly affect the dynamic properties in the low temperature regime.