(NH4)4(PFeIIIMoVI11O40H2).9H2O (yellow) and (NH4)4(PFeIIIMoVMoVI10O40H3).11H2O (blue) were synthesized. The Moessbauer spectra of the 2 heteropoly acid salts were determine using 57Fe isotropic enrichment. The IR spectra and magnetic susceptibility were obtained. Splitting Qs can be used as an indication of distortion degree of MO6 (M = Mo, Fe) octahedra in Keggin structures. There is super exchange interaction between MoV and FeIII through Mo(V)-O-Fe(III) bridge in Keggin structure.

Key words: HETEROPOLYACID, MOLYBDATE, PHOSPHATE, FERRATE, CHLOROACETIC ACID, MOSSBAUER SPECTROMETRY, AMINE SALT