The iron phosphonates, tris (methyl methylphosphonate) iron (III) [Fe(MMP)3]; tris (ethylphosphonate) iron (III) [Fe(EEP)3]; and tris (isopropyl methylphosphonate) iron (III) [Fe(EEP)3]; have been obtained and studied previously by infrared spectroscopy and elemental analysis.1The infrared obsorption spectra of the iron phosphonate compounds exhibited bands which could be assigned to functional groups of the phosphonate ligand; however, the role played by the iron atom in the molecule was unknown. In the present article, the results of Mössbauereffect spectroscopy are used to provide evidence for the interaction of the iron with the phosphonate esters.