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

Abstract

A seven-coordinate FeIII complex, [Fe(oda)(H2O)2(NO3)], was obtained after dissolving Fe(NO3)3 Æ 9H2O in an aqueous solution of oxydiacetic acid (H2oda) at room temperature. In the solid state, the FeIII center adopts a pentagonal bipyramid geometry with an {FeO7} core formed by a tridentate oda2- 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 FeIII centers with rhombic zero field splitting parameters (D = 0.81 cm-1, E/ D = 0.33 ). Weak antiferromagnetic interactions with J aprox -0.06 cm-1 operating between neighboring Fe ions connected through Fe–O–C–O...H–O–Fe paths are estimated using the molecular field approximation.