Synthesis and Characterization of Symmetrically versus Unsymmetrically Proton-Bridged Hexa-Iron Clusters

Syntheses and magnetic structural characterization of hexa-iron complexes derivatized salicylaldoximes are discussed. Complexation Fe(BF4)2·6H2O with each ligand (H2L1 H4L2) in a methanolic-pyridine solution resulted compounds (C1 C2, respectively), which contain two near-parallel metal triangles [Fe3–μ3-O], linked by six fluoride bridges stabilized hydrogen-bonded proton between the μ3-O groups. Within triangle Fe(III) ions connected via amine “straps” (H4L2-2H). Variable-temperature susceptibility Mössbauer data C1 C2 indicate presence dominant antiferromagnetic interactions high-spin (S = 5/2) centers. For C1, quadrupole doublets observed at room temperature 5 K, consistent from discrete but disordered [Fe3–μ3-O] [Fe3–μ3-OH] species were inferred. single sharp doublet splitting intermediate those determined for was observed, symmetric [Fe3–μ3-O···H···μ3-O–Fe3] inferred crystallographically very short μ3-O···μ3-O separation. The differences physical properties complexes, as seen Mössbauer, X-ray, data, attributed to conformational flexibility imparted nature linkages closely related ligands.