A Dy2 single-molecule magnet with benzoate anions and phenol-O− bridging groups

Abstract

A Dy₂ single-molecule magnet, namely [Dy₂(H₃L)₂(PhCOO)₄]·4H₂O (1), was obtained from the reaction of Dy(PhCOO)₃ with 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonohydrazide (H₄L). Each Dy^III ion is located in the chelating pocket [DyO₈N] formed by the carboxyl-O, phenol-O, carbohydrazide-O and carbohydrazide-N, forming a tricapped trigonal prism configuration. The Dy^III centers are bridged by the benzoate anions with μ₂:η¹,η² coordination mode and the phenol-O⁻ groups in the form of μ₁:η², respectively. The appearance of frequency-dependent out-of-phase (χ′′_M) signals indicates that 1 displays single-molecule magnet (SMM) behaviour. Fits of the ac data gave an energy barrier (U_eff) of 42.7 K with a pre-exponential factor (τ₀) of 1.31 × 10⁻⁷ s. The structure–property relationship of some selected Dy₂ paradigmatic compounds was further discussed.