Single-molecule magnetism in CoIII2DyIII2-amine-polyalcohol-acetylacetonate complexes: effects of ligand replacement at the Dy $^III$ sites on the dynamics of magnetic relaxation

The article describes the structures, magnetism and ab initio theory of three new “butterfly” CoIII2DyIII2(OH) 2 clusters containing alcoholamine ligands and six bidentate acetylacetonate ligands, per cluster. The synthesis of three new tetranuclear heterometallic Co III –Dy III planar butterfly coordination complexes is reported of molecular formulae [DyIII2CoIII2(OH) 2 (teaH) 2 (acac) 6 ]·MeCN ( 3 ), [DyIII2CoIII2(OH) 2 (bdea) 2 (acac) 6 ]·2H 2 O ( 4 ) and [DyIII2CoIII2(OH) 2 (edea) 2 (acac) 6 ]·2H 2 O·4MeCN ( 5 ) (teaH 3 = triethanolamine, bdeaH 2 = N-n -butyldiethanolamine, edeaH 2 = N -ethyldiethanolamine and acacH = acetylacetone) each of which display single-molecule magnet (SMM) behaviour. Importantly these new compounds are related to several CoIII2DyIII2 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.