Single-molecule magnetism in {Co III2Dy III2}-amine-polyalcohol-acetylacetonate complexes: effects of ligand replacement at the DyIII sites on the dynamics of magnetic relaxation

Abstract

The synthesis of three new tetranuclear heterometallic Co^III–Dy^III planar butterfly coordination complexes is reported of molecular formulae [Dy^III₂Co^III₂(OH)₂(teaH)₂(acac)₆]·MeCN (3), [Dy^III₂Co^III₂(OH)₂(bdea)₂(acac)₆]·2H₂O (4) and [Dy^III₂Co^III₂(OH)₂(edea)₂(acac)₆]·2H₂O·4MeCN (5) (teaH₃ = triethanolamine, bdeaH₂ = N-n-butyldiethanolamine, edeaH₂ = N-ethyldiethanolamine and acacH = acetylacetone) each of which display single-molecule magnet (SMM) behaviour. Importantly these new compounds are related to several {Co^III₂Dy^III₂} SMM compounds allowing for the study of the effect that the subtle changes in structure have on the SMM properties. Ab initio calculations are performed on 3–5, as well as on the related structural derivatives in order to gain insight on the effect the structural changes have on the dynamic magnetic behaviour.