A seven-co ordinate FeIII compound:: [Fe{O(CH2CO2)2}(H2O)2(NO3)].: Preparation, structure and magnetic properties

A seven-coordinate Fe-III complex, [Fe(oda)(H2O)(2)(NO3)], was obtained after dissolving Fe(NO3)(3)center dot 9H(2)O in an aqueous solution of oxydiacetic acid (H(2)oda) at room temperature. In the solid state, the Fe-III center adopts a pentagonal bipyramid geometry with an {FeO7} core formed by a tridentate oda(2-) and a bidentate NO3- in the equatorial plane, and two axial water molecules. Magnetic measurements and EPR spectra revealed the presence of S=5/2 Fe-III centers with rhombic zero field splitting parameters (D=0.81 cm(-1), E/D=0.33). Weak antiferromagnetic interactions with J approximate to-0.06 cm(-1) operating between neighboring Fe ions connected through Fe-O-C-O center dot center dot center dot H-O-Fe paths are estimated using the molecular field approximation. (C) 2007 Elsevier B.V. All rights reserved.