Three Dy(iii) single-ion magnets bearing the tropolone ligand: structure, magnetic properties and theoretical elucidation

Abstract

The reactions of dysprosium nitrate with the main ligand of tropolone (HL) in the presence of ancillary ligands of phenanthroline (phen) or 1,3,5-benzenetricarboxylic acid (H₃BTC) gave three mononuclear complexes, [Dy(phen)₂(L)(NO₃)₂] (1), [Dy(phen)(L)₃]·H₂O (2) and [Dy(H₃BTC)(H₂O)(L)₃]₂·3H₂O (3). They present different sets of mixed ligands. The Dy(III) ions are ten-coordinated to build a bicapped square anti-prismatic geometry for complex 1 and eight-coordinated in dodecahedral geometries for complexes 2 and 3. Their magnetic properties were investigated in detail. Complexes 1 and 2 are single ion magnets under an external field, and complex 3 is a single ion magnet under zero field. This revealed a tuning effect on the performances of single ion magnets from ancillary ligands. These experimental magnetic behaviours are supported by the results from ab initio calculations, including g-tensors, averaged transition magnetic moments, magnetic easy axes, and crystal field parameters.