Dipotassiumtetrachloride-bridged dysprosium metallocenes: a single-molecule magnet.

The present work describes the dynamic magnetic properties of the complex [(Cp Ar3 ) 4 DyIII2Cl 4 K 2 ]·3.5(C 7 H 8 ) (1), synthesized by employing a tri-aryl-substituted cyclopentadienyl ligand (Cp Ar3 ), [4,4'-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) = Cp Ar3 H]. Each Dy(III)-metallocene weakly couples via K 2 Cl 4 , displaying slow relaxation of magnetization below 14.5 K under zero applied dc field via KD3 energy levels with an energy barrier of 136.9/133.7 cm -1 on the Dy sites. The single-ion axial anisotropy energy barrier is reduced by geometrical distortion due to the coordination of two chloride ions at each Dy centre.