Strategy for the Rational Design of Asymmetric Triply Bridged Dinuclear 3d-4f Single-Molecule Magnets.

Three triply bridged MII-DyIII dinuclear complexes, [Ni(μ-L)(μ-OAc)Dy(NO3)2] 1, [Zn(μ-L)(μ-OAc)Dy(NO3)2] 2, and [Ni(μ-L)(μ-NO3)Dy(NO3)2]·2CH3OH 3 were prepared with a new and flexible compartmental ligand, N,N′,N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylene triamine (H2L), containing N3O2-inner and O4-outer coordination sites. These complexes have diphenoxo/acetate (1 and 2) or diphenoxo/nitrate (3) asymmetric bridging fragments. Compounds 1 and 3 exhibit ferromagnetic interaction between Ni2+ and Dy3+ ions and frequency dependence of the out-of-phase (χ″M) alternating current (ac) susceptibility signal characteristic of single-molecule-magnet behavior. The energy barriers Δ/kB for compound 3 under zero and 1000 Oe applied direct current (dc) magnetic fields were estimated from the Arrhenius plots to be 7.6 and 19.1 K, respectively.