Abstract
The encapsulating N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H(2)valdien) ligand was employed to isolate two novel Dy-III compounds which contain rare bridging pathways for lanthanide systems. Compound 1, [(NaDy2III)-Dy-2(valdien)(2)(mu-OH)(dbm)(2)(H2O)(2)][Na2Dy2III(valdien)(2)(mu-OH)(NO3)(2)(dbm)(2)], where dbm(-) is dibenzoylmethanido, and compound 2, [Na3Dy2III(valdien)(2)(mu-F)(mu(3)-F)(Cl)(2)(MeOH)(2)](n)center dot 0.5(MeOH)center dot(H2O), both exhibit linear lone hydroxo- and fluoro-bridges, respectively, between the metal centers. The unit cell of 1 comprises two discrete dinudear 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 Dy-III ions. Magnetic susceptibility measurements in the temperature range 1.8-300 K reveal that the Dy-III 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 arising from the fluoride-bridge, leads to zero-field single-molecule magnet (SMM) behavior with a non-negligible anisotropy barrier (U-eff) of 42 K.