Slow Magnetic Relaxation Observed in Dysprosium Compounds Containing Unsupported Near-Linear Hydroxo- and Fluoro-Bridges

The encapsulating N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) ligand was employed to isolate two novel DyIII compounds which contain rare bridging pathways for lanthanide systems. Compound 1, [Na2DyIII2(valdien)2(μ-OH)(dbm)2(H2O)2][Na2DyIII2(valdien)2(μ-OH)(NO3)2(dbm)2], where dbm– is dibenzoylmethanido, and compound 2, [Na3DyIII2(valdien)2(μ-F)(μ3-F)2(Cl)2(MeOH)2]n·0.5(MeOH)·(H2O), both exhibit linear lone hydroxo- and fluoro-bridges, respectively, between the metal centers. The unit cell of 1 comprises two discrete dinuclear molecules, which differ slightly, forming a cation–anion pair, while 2 forms a coordination polymer. The magnetic investigations indicate that both compounds display ferromagnetic coupling between the DyIII ions. Magnetic susceptibility measurements in the temperature range 1.8–300 K reveal that the DyIII ions in 1 are weakly coupled, resulting in a mononuclear single-molecule magnet-like behavior under an applied field. In the case of 2, the stronger coupling ari...