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Issue 5, 1996
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Organometallic cation-exchanged phyllosilicates: variable-temperature 57Fe Mössbauer spectroscopic and related studies of the adsorption of dimethylaminomethylferrocene on clays and pillared clays

Abstract

Variable-temperature 57Fe Mössbauer spectroscopy, thermogravimetry (TG), powder X-ray diffraction (PXRD) and temperature-programmed solid insertion probe mass spectrometry (TP-SIP-MS) have been used to study the interaction of dimethylaminomethylferrocene (DMAMF) with Westone-L (WL), a low iron montmorillonite. The hydrochloride salt of DMAMF, (ferrocenylmethyl)dimethylammonium chloride (FMDMACl), was prepared and studied both prior and subsequent toexchange on the interlamellar sites of WL. X-Ray diffraction confirmed that the FMDMA+ cations were incorporated between the clay lamellae and the observed spacing of 15.1 Å was thermally stable up to 200 °C in air. TP-SIP-MS indicated that a small proportion of the incorporated metallocene was volatilised at temperatures below 400 °C, but that the majority decomposed via loss of cyclopentadienyl ligands leaving the metal centre between the sheets. A similar thermal degradation path was observed for DMAMF on aluminium pillared clay (Al-PILC). 57Fe Mössbauer spectroscopy revealed that the FMDMA+ cation occupied a similar environment in the chloride salt, FMDMA+–WL and DMAMF–Al-PILC insofar as the isomer shift, 6, and quadrupole splitting, Δ, of the incorporated metallocene were essentially the same in all complexes and virtually identical to that observed for FMDMACl(δ= 0.34 mm s–l, δ= 2.32 mm s–l at 300 K). The values for the Debye temperature θ, and recoil-free fraction f determined from variable-temperature 57Fe Mössbauer spectroscopy, were typically 140 K and 0.12, respectively, for FMDMACl and FMDMA+–WL, thus confirming the similar environment occupied by the cation in the chloride salt and in WL. In contrast, the corresponding values for DMAMF–A1-PILC were 118 K and 0.06, respectively, indicating that the the metallocene enjoyed much greater freedom in the galleries of the Al-PILC which exceed the dimensions of the metallocene compared to FMDMA+-WL where the organoiron cation itself determines the layer separation.

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Article type: Paper
DOI: 10.1039/JM9960600849
Citation: J. Mater. Chem., 1996,6, 849-859
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    Organometallic cation-exchanged phyllosilicates: variable-temperature 57Fe Mössbauer spectroscopic and related studies of the adsorption of dimethylaminomethylferrocene on clays and pillared clays

    C. Breen, J. S. Brooks, S. Forder and J. C. E. Hamer, J. Mater. Chem., 1996, 6, 849
    DOI: 10.1039/JM9960600849

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