Influencing the properties of dysprosium single-molecule magnets with phosphorus donor ligands

Abstract

Single-molecule magnets are a type of coordination compound that can retain magnetic information at low temperatures. Single-molecule magnets based on lanthanides have accounted for many important advances, including systems with very large energy barriers to reversal of the magnetization, and a di-terbium complex that displays magnetic hysteresis up to 14 K and shows strong coercivity. Ligand design is crucial for the development of new single-molecule magnets: organometallic chemistry presents possibilities for using unconventional ligands, particularly those with soft donor groups. Here we report dysprosium single-molecule magnets with neutral and anionic phosphorus donor ligands, and show that their properties change dramatically when varying the ligand from phosphine to phosphide to phosphinidene. A phosphide-ligated, trimetallic dysprosium single-molecule magnet relaxes via the second-excited Kramers' doublet, and, when doped into a diamagnetic matrix at the single-ion level, produces a large energy barrier of 256 cm−1 and magnetic hysteresis up to 4.4 K.

Phosphinidene-bridged binuclear complexes

“…An example of stable anionic phosphinidene complexes prepared by the deprotonation route was recently reported by Layfield and co-workers, who isolated the [Li(THF) 4 ]  salts of complexes 24 and 25 (Scheme 13), which exhibit interesting magnetic properties and were characterised through an X-ray study [38].…”

Molecular single-ion magnets based on lanthanides and actinides: Design considerations and new advances in the context of quantum technologies

“…The loop width generally increases with a decrease of temperature and with an increase of the field-charging rate [32]. The most used method for detecting and characterising slow magnetic relaxation is through the use of alternating current (ac) magnetic susceptibility measurements [65][66][67][68][69][70]. Wherein, a small oscillating magnetic field is applied to the sample, and the in-phase and out-of-phase components of magnetic susceptibility are measured over a range of temperatures, oscillation frequencies, and static magnetic fields.…”

Strong direct exchange coupling and single-molecule magnetism in indigo-bridged lanthanide dimers

“…6 Thus, assuming that the easy axis of magnetization in 1 Dy and 2 Dy is oriented towards the [Cp*] -ligands, as has been determined through theoretical studies of many exemplar systems, 6,7 the hard oxygen and nitrogen donors can be regarded as residing in hard (equatorial) plane. As such, the diminished axiality of the Dy 3+ ion enables efficient relaxation via processes that shortcut the maximum possible thermal energy barrier, hence the low observed U eff values for these systems.…”