Single-Molecule Magnet Properties in 3<i>d</i>4<i>f</i> Heterobimetallic Iron and Dysprosium Complexes Involving Hydrazone Ligand

The reaction between the ((<i>E</i>)-<i>N</i>′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide) (H₂opch) ligand and the metallo-precursor [Dy(hfac)₃]·2H₂O led to the formation of an homometallic coordination complex with the formula [Dy₂(hfac)₃(H₂O)(Hopch)₂][Dy(hfac)₄] (<b>1</b>). In presence of both [Dy(hfac)₃] 2H₂O and the Fe(II) salt, the heterobimetallic tetranuclear [FeDy₃(hfac)₈(H₂O)₂(opch)₂] (<b>2</b>) was isolated, while the addition of the co-ligand 1,2-Bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H₂bmh) led to the formation of two heterobimetallic tetranuclear complexes with the formula [Fe₃Dy(hfac)₆(opch)₂(H₂bmh)] C₆H₁₄ (<b>3</b>) <b>C₆H₁₄</b> and [Fe₂Dy₂(hfac)₇(opch)₂(H₂bmh)] 0.5C₇H₁₆ (<b>4</b>) <b>0.5C₇H₁₆</b>. Single crystal X-ray diffraction and dc magnetic investigation demonstrated that <b>3</b> and <b>4</b> involved the iron center in the +II and +III oxidation states. Dynamic magnetic measurements highlighted the single-molecule magnet behavior of <b>1</b> and <b>2</b> in a zero applied dc field primarily due to the ferromagnetic interactions taking place in these compounds.