SMM Behaviour of the Butterfly {Cr ^III ₂ Dy ^III ₂ } Pivalate Complex and Magneto‐structurally Correlated Relaxation Thermal Barrier

Abstract We are reporting the synthesis, single‐crystal X‐ray structure characterization, and magnetic property investigations of the pivalate butterfly {Cr III 2 Ln III 2 } complexes with Ln= Gd and Dy and the isostructural Y(III) sample. We found an anti‐ferromagnetic Cr(III)‐Ln(III) exchange interaction, which, as previously observed in related Cr(III)/Ln(III) systems, plays a key role in suppressing quantum tunnelling of magnetization and enhances the SMM performance in the Dy(III) complex. In fact, a pure Orbach relaxation mechanism, with absence of QT regime, is observed with a thermal barrier of 50 cm −1 , leading to magnetization hysteresis opening, measured with a commercial magnetometer, up to 3.6 K with a coercive field of 2.9 T. Analysis of SMM behaviour in literature‐known butterfly {Cr III 2 Dy III 2 } complexes, reveals the existence of a magneto‐structural correlation between U eff , the thermal barrier size, and the mean Cr−Dy bond distances. Moreover, a clear correlation is found for the thermal barrier magnitude and the maximum temperature hysteresis opening and coercive field.