Synthesis and structural studies of iron(II) and iron(III) sulfonates

The iron(II) sulfonates Fe(CF3SO3)2 and Fe(p-CH3C6H4SO3)2 have been prepared and on the basis of vibrational and electronic spectra and magnetic and MÖssbauer data have been assigned a layer lattice structure involving hexacoordinated iron(II) and terdentate bridging anions. The FeO6 chromophore in these compounds is distorted by a trigonal elongation along the C3 axis. Fe(CH3SO3)2 has been obtained in two isomeric forms, one having a trigonal elongation of the FeO6 chromophore, the other a trigonal compression. No structural isomerism has been found for the other iron(II) sulfonates; however, evidence for such isomerism in methanesulfonates of cobalt(II) and zinc(II) is presented. While Fe(CF3SO3)2 and Fe(p-CH3C6H4SO3)2 appear to be magnetically dilute the presence of antiferromagnetic coupling in both forms of Fe(CH3SO3)2 is indicated. The iron(III) sulfonates, Fe(CF3SO3)3, Fe(p-CH3C6H4SO3)3, and Fe(CH3SO3)3, have been prepared and all three are magnetically concentrated exhibiting magnetic moments which are significantly less than 5.92 BM and which decrease with decreasing temperature.