An unprecedented zigzag-shaped heptanuclear ferric cluster: synthesis, structure and magnetism

The synthesis, crystal structure and magnetochemical characterization are reported for a new FeIII7 cluster, [FeIII7(L)4(O2CPh)8(H2O)2]NO3·3CH3CN (1). Complex 1 was synthesized from the use of the potentially O,N,O,O tetradentate chelate, 3-(2-hydroxybenzylideneamino)propane-1,2-diol (H3L), in the presence of carboxylate groups. Inspection of the central core reveals that it contains two triangular subunits sharing a common vertex Fe2, and then the vertex Fe3 (Fe3A) is further bonded to Fe4 (Fe4A) by a μ2-Oalkoxide atom from the L3 − ligand, generating the unprecedented zigzag arrangement heptanuclear Fe7 unit. Variable temperature magnetic susceptibility studies for 1 reveal the presence of only antiferromagnetic exchange interactions. Complex 1 shows no evidence of slow relaxation behavior above 2.0 K.