Air-stable chiral mono- and dinuclear dysprosium single-molecule magnets: steric hindrance of hexaazamacrocycles

Abstract

Mononuclear [Dy(L¹_R/S)(4-Me-PhO)₂](BPh₄) (1R/1S) and dinuclear [Dy₂(L²_R/S)₂(4-Me-PhO)₂(OH)₂](BPh₄)₂ (2R/2S) chiral dysprosium(III) complexes were synthesized using equatorial hexaazamacrocycle and p-cresol axial ligands. Structural and magnetic analyses revealed that 1R/1S are high-performance single-molecule magnets due to their nearly perfect D_6h local symmetry. Hydroxo-bridged dinuclear species 2R/2S with nine-coordinate hula-hoop geometry possess strong intramolecular ferromagnetic interactions as proven by the electrostatic model, suppressing quantum tunnelling of magnetization (QTM) to some extent.