FE-57 MOSSBAUER SPECTROSCOPIC STUDIES OF THE FERROCENE MOLECULAR-REORIENTATION IN ALPO4-5 AND ALPO4-8 FRAMEWORKS

Fe-57 Mossbauer spectroscopic studies were carried out on ferrocene gu est molecules in some microporous aluminium phosphate host lattices in order to investigate their behaviour in the aluminium phosphate chann els. The 300 K spectra show broad single lines with isomer shifts of 0 .39 and 0.41 mm s-1 relative to iron for AlPO4-5:ferrocene and AlPO4-8 :ferrocene inclusion compounds, respectively. The absence of quadrupol e splittings for these materials contrasts with the large quadrupole s plitting observed for ferrocene itself at the same temperature. The lo w-temperature spectrum (20 K) for AlPO4-5:ferrocene shows a doublet wi th quadrupole splitting of 2.37 mm s-1 and an isomer shift of 0.55 mm s-1. The collapse of the quadrupole splitting at room temperature is c onsistent with the ferrocene molecules rotating within the channels.