Single-Molecule Magnet Rods: Remarkably Elongated Lanthanide Phosphonate Cores with Quasilinear Hydrazones.

Large metal-phosphonate clusters typically exhibit regular polyhedral, wheel-shaped, spherical, or capsule-shaped morphologies more effectively than high-aspect ratio topologies. A system of elongated lanthanide core topologies has now been synthesized by the reaction of lanthanide 1-naphthylmethylphosphonates and four differently terminated pyrazinyl hydrazones. Four new rod-shaped dysprosium phosphonate clusters, [Dy 6 (O 3 PC 11 H 9 ) 4 (L 1 ) 4 (μ 4 -O)(DMF) 4 ]·2DMF·3MeCN·3H 2 O ( 1 ), [Dy 8 (O 3 PC 11 H 9 ) 4 (L 2 ) 4 (μ 3 -O) 4 (CO 2 ) 4 (H 2 O) 4 ]·6DMF·4MeCN·3H 2 O ( 2 ), [Dy 12 Na(O 3 PC 11 H 9 ) 6 (L 3 ) 6 (μ 3 -O) 2 (pyr) 6 ]·DMF·2MeCN·H 2 O ( 3 ), and [Dy 14 (O 3 PC 11 H 9 ) 12 (L 4 ) 8 (μ 3 -O) 2 (DMF) 4 (MeOH) 2 (H 2 O) 4 ]·5DMF·2MeCN·H 2 O ( 4 ), were obtained. Four single-pyrazinyl hydrazones function as pentadentate bis-chelate terminal co-ligands, coordinating the periphery of dysprosium phosphonate rods. A sodium ion serves as a cation template for constructing heterobimetallic 3 by occupying the void, demonstrating the ability to reliably control cluster length by modifying the hydrazone co-ligand structure and cation template. Additionally, it was observed that the elongation of the rods has a significant directional impact on the magnetic relaxation behavior, transitioning from a one-step process in 1 to a three-step process in 2 , a two-step process in 3 , and finally a two-step process in 4 .