SYNTHESIS AND CRYSTAL-STRUCTURE OF A 7-COORDINATE DINUCLEAR IRON(III)COMPLEX CONTAINING ONLY BIDENTATE LIGANDS

A novel seven-coordinate dinuclear iron(III) complex, [Fe-2(O)(NO3)(4) (bpy)(2)] (1) (bpy = 2,2'-bipyridine), with a linear Fe-O-Fe bridge ha s been prepared and characterized by X-ny crystallography and magnetic susceptibilities. Each iron atom of 1 has a distorted pentagonal-bipy ramidal geometry in which four oxygen atoms of two bidentate nitrate l igands and one nitrogen atom of bpy form the pentagonal plant. The oth er nitrogen atom of bpy and the bridging oxo ion occupy the axial posi tions. The iron-iron and iron-oxo distances are 3.550(3) and 1.775(1) Angstrom, respectively. The -J value of 104 cm(-1) for 1 indicates the presence of an antiferromagnetic interaction due to superexchange cou pling between two iron(III) ions via an ore-bridge. (C) 1998 Elsevier Science S.A. All rights reserved.