Molecular systems that possess a thermal barrier to reorientation of their magnetic moment—known as single molecule magnets—have attracted significant attention in the last two decades due to their possible applications in data storage, quantum computing, and molecular spintronics. Most systems to date have involved transition metals and lanthanides, though considerable interest in actinide-based single molecule magnets has grown within the last five years due to their greater spin-orbit coupling, greater crystal field splitting, and more diffuse valence f orbitals when compared with the lanthanides. Unfortunately, the supposed benefits of actinide-based systems have yet to materialize, limited by the sparse number of actinide-based single molecule magnets reported in the literature, and by the conflict between experimental and computational effective barriers to relaxation, Ueff. As such, the rational design and study of actinide single-molecule magnets is particularly challenging. Though much of the research on actinide-based systems has focused on UIII, UV has shown great promise due to its high Ising-type anisotropy and large crystal field splitting. Here, we present a series of mononuclear UV complexes in which the axial anisotropy is established through the coordination of hard donor atoms, e.g. oxo and halide ligands. The effects of various axial ligand field strengths on UV magnetism are discussed. The terminal-oxo complex UV(O)[N(Si(Me)3)2]3 is shown to exhibit a Ueff of 30 cm–1, the second-highest thermal barrier reported for a mononuclear uranium system, and the highest overall barrier to magnetic relaxation for any UV mononuclear system.

Probing slow magnetic relaxation in a series of mononuclear uranium (v) compounds

253rd National Meeting (2017)

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