Using N-Heterocyclic Carbenes as Weak Equatorial Ligands to Design Single-Molecule Magnets: Zero-Field Slow Relaxation in Two Octahedral Dysprosium(III) Complexes

We report the synthesis, structures, and magnetic investigations of two new octahedral dysprosium complexes, based on the original N-heterocyclic carbene (NHC) tridentate bis(phenoxide) ligand, of the respective formulas mer-[DyL(THF)(2)Cl] (1) and mer-[DyL(THF)(3)][BPh4] (2), where L = 1,3-bis(3,5-di-tert-butyl-2-oxidophenyl)-5,5-dimethyl-3,4,5,6-tetrahydropyrimidin-1-ium chloride and THF = tetrahydrofuran. The short Dy-O distances in the axial direction in association with the weak donor ability of the NHC moiety provide a suitable environment for slow relaxation of magnetization, overcoming the previous single-molecule magnets based on NHC ligands.

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We report the synthesis, structures, and magnetic investigations of two new octahedral dysprosium complexes based on the N-heterocyclic carbene (NHC) tridentate bis(phenoxide) ligand. These complexes exhibit suitable features for slow relaxation of magnetization by utilizing the short Dy-O distances in the axial direction and the weak donor ability of the NHC moiety.