Synthesis and magnetic properties of terephthalato-bridged binuclear iron (II) complexes

摘要

Four new Fe(II)-Fe(II)μ-terephthalato binuclearcomplexes have been synthesized and characterized, namely[Fe2(TPHA)L4]SO4, [L=2,2'-bipyridine (bpy); 1, 10-phenanthroline (phen); 5-methyl-1,10-phenanthroline (Me-phen);5-nitro-1, 10-phenanthroline (NO2-phen)], where TPHA is theterephthalate dianion. Based on elemental analyses, molarconductance and magnetic moments of room-temperaturemeasurements, and spectroscopic studies, extended TPHA-bridgedstructures consisting of two iron (II) ions each in an octahedralenvironment, are proposed for these complexes. The[Fe2(TPHA)(bpy)4]SO4(1) and [Fe2(TPHA(phen)4)SO4(2)complexes were characterized by variable temperature magneticsusceptibility (4-300K) measurements and the observed data weresuccessfully simulated by the equation based on the spinHamiltonian operator, H=-2JS1?S2, giving the exchange integralsJ=-3.92 cm-1 for (1) and J=-2.46 cm-1 for (2). This resultindicates the presence of a weak antiferromagnetic spin-exchangeinteraction between the metal ions within each molecule