Self-Assembly of Lanthanide-Based Single-Ion Magnets into 1D Networks via Re(IV)-Based Metalloligands

This work reports the synthesis, crystal structure, magnetic properties, and theoretical calculations of a family of one-dimensional Re(IV)–Ln(III) coordination complexes obtained through the "complex-as-ligand" strategy. Using pyridinedicarboxylic acid derivatives to form [ReBr₅(3,4-pydcH₂)]⁻ and [ReBr₅(3,5-pydcH₂)]⁻ metalloligands, five new heteropolynuclear compounds were prepared with Dy(III), Tb(III), and Gd(III) ions. Two of the Dy-containing complexes exhibit field-induced slow relaxation of the magnetisation, consistent with single-ion magnet (SIM) behaviour, as confirmed by ac magnetic susceptibility measurements. Structural analyses reveal that intra- and intermolecular Br···Br halogen contacts play a significant role in shaping the magneto-structural properties across the series. DFT and NEVPT2 calculations support the experimentally derived magnetic parameters, validating the proposed models. These results highlight the versatility of combining highly anisotropic 5d (Re(IV)) and 4f (Ln(III)) ions for building magnetically functional, one-dimensional molecular materials with potential applications in molecular spintronics and information storage.