A Novel Tetranuclear Iron Complex [Fe4O2(O2CC2H5)7(bipy)2]PF6.2H2O (bipy=2,2'-Bipyridine):Synthesis, Crystal Structure and Magnetic Properties

A novel tetranuclear iron-oxo complex has been synthesized and characterized by X-ray single crystal structural analysis: [Fe4O2(O2CC2H5)7(bipy)2]PF6_2H2O (bipy = 2,2_- bipyridine). The title complex crystallizes in the monoclinic system, space group C2/c, with lattice parameters a = 27.859(2) A, b = 13.0629(10) A, c = 17.2698(14) A, _ = 123.6080(10)_, V = 5234.3 (7) A3, Dc = 1.559 Mg/m3, Z = 4, R1 = 0.0493. The molecular structure shows that there are two types of coordination environment for Fe(III) atoms. One is formed by two N atoms and four O atoms, another by six O atoms, all in distorted octahedron, which forms a "butterfly" core structure. The corresponding variable temperature susceptibility measurement shows the antiferromagnetic interactions in the complex.