Chemistry of iron complexes: Part X-An ESR spectral study of iron (III) complexes with triphenylphoshine oxide and 1,2-ethylenebis(diphenylphosphine oxide)

Abstract

An ESR spectral study of complexes of iron (III) with triphenylphosphine oxide (Ph₃PO) and 1,2- ethylenebis(diphenylphosphine) oxide(edpo), namely, [FeX₂(Ph₃PO)₄][FeX₄] (<strong>1, 2</strong>); [FeX₂(edpo)₂][FeX₄] (<strong>3, 4</strong>); [FeI₂(Ph₃PO)₄][FeCI₄] (<strong>5</strong>) (X=Cl, Br) and [Fe(NO₃)₃(Ph₃PO)₂] (<strong>6</strong>) is reported. The effect of heat treatment on the compounds has been studied with a view to investigating the effect of phase transformations on the ESR spectra. The study was carried out by initially heating a given sample for an hour then recording its ESR spectrum after cooling it to room temperature (30&deg;C). The correlation of the ESR data with the presence of <em>cis, trans </em>isomers, the effect of chelation by ligand on the stability of a compound and the selective replacement of chlorine atoms from the cation of complex (<strong>1</strong>) by iodine atoms are discussed.