Slow magnetic relaxation in homoleptic trispyrazolylborate complexes of neodymium(III) and uranium(III).

Lanthanide- and actinide-based single-molecule magnets are rapidly gaining prominence due to the unique properties of f-orbitals, yet no direct comparison of slow magnetic relaxation of an isostructural and valence isoelectronic lanthanide and actinide complex exists. We present the dynamic magnetic properties of two f-element single-molecule magnets, NdTp(3) and UTp(3) (Tp(-) = trispyrazolylborate), demonstrating that, although neither complex displays the full anisotropy barrier predicted from its electronic structure, relaxation is slower in the uranium congener. Magnetic dilution studies performed with NdTp(3) reveal that, while intermolecular interactions partially account for the faster relaxation dynamics, they are not uniquely responsible.