Pentagonal Bipyramidal Ln(III) Complexes Containing an Axial Phosphine Oxide Ligand: Field-induced Single-ion Magnetism Behavior of the Dy(III) Analogues

Abstract

A series of neutral homologous complexes [(L)Ln(Cy₃PO)Cl] {where Ln = Gd (<b>1</b>), Tb (<b>2</b>), Dy (<b>3</b>), and Er (<b>5</b>)} and [(L)Dy(Ph₃PO)Cl] (<b>4</b>) [H₂L = 2,6-diacetylpyridine <i>bis</i>-benzoylhydrazone] were isolated. In these complexes, the central lanthanide ion possesses a pentagonal bipyramidal geometry with an overall pseudo <i>D</i>_5<i>h</i> symmetry. The coordination environment around the lanthanide ion comprises of three nitrogen and two oxygen donors in an equatorial plane. The axial positions are taken up by a phosphine oxide (O donor) and a chloride ion. Among these compounds, the Dy(III) (<b>3</b> and <b>4</b>) analogues were found to be field-induced single-ion magnets.