Strong Antiferromagnetic Exchange‐Coupling Observed in Hydride‐Bridged Dimeric Dysprosium(III) Single‐Molecule Magnet

Abstract

Comprehensive SummaryOne dihydride‐bridged dimeric Dy(III) guanidinate complex, formulated as [{(Me3Si)2NC(NiPr)2}2Dy(μ‐H)]2 (1Dy), was successfully isolated and the introduction of hydride bridges significantly reduces the intramolecular Dy(III)···Dy(III) distance to only 3.688(1) Å. To investigate the effect of such a short Dy(III)···Dy(III) distance on magnetism, we also prepared its dibromide‐bridged analogue [{(Me3Si)2NC(NiPr)2}2Dy(μ‐Br)]2 (2Dy), which has a much longer Dy(III)···Dy(III) distance of 4.605(4) Å. Surprisingly, 2Dy demonstrates much larger effective energy barrier for magnetization reversal (Ueff) and higher blocking temperature (TB). The worse performance of 1Dy is attributed to the concerted effect of strong antiferromagnetic interactions between Dy(III) ions (Jtotal = –2.683 cm–1) and the unparallel arrangement of magnetic principle axes of the Dy(III) ions for 1Dy.