Synthesis and Characterization of Iron(III) Complexes of a New Ligand Containing a Potentially Bridging Carboxylate; Structural Characterization of Helical Tetranuclear Iron Complex

Reaction of the new polydentate ligand 2,6-bis{3-[N,N-di(2-pyridylmethyl)amino]propoxy}benzoic acid (LH) with Fe(ClO4)3 followed by addition of chloroacetic acid leads to the formation of the tetranuclear complex [{Fe2OL(ClCH2- CO2)2}2](ClO4)4, the crystal structure of which reveals that it consists of two FeII2(µ-O)(µ-RCO2)2 cores that are linked via the two L ligands in a helical structure, with the carboxylate moieties of the two ligands forming a hydrogen-bonded pair at the center of the helix.