Organo-iron compounds on clays and pillared clays.

HAMER, Julian C. E. (1998). Organo-iron compounds on clays and pillared clays. Doctoral, Sheffield Hallam University (United Kingdom)..

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Abstract

(Ferrocenylmethyl)dimethylammonium chloride has been synthesised and the cation intercalated into the montmorillonite Westone-L. Variable temperature Mossbauer spectroscopy indicated that the molecule had a similar Debye temperature in each environment (144 +/- 5 K and 140 +/- 5 K respectively). The intercalated Mossbauer spectra revealed a Karayagin effect above 80 K. The cation occupies 80 % of the total exchange capacity of the clay, most likely orientated with the cyclopentadienyl rings perpendicular to the silicate layers. Thermal decomposition of the intercalate involved the volatilisation of iron containing fragments below 350°C. Variable-temperature XRD showed the intercalated sample had a d[001]-spacing of 1.55 nm at room temperature, which decreased at 200°C to give a d[001]-spacing of 1.3 nm. An iron oxide probably remains within the interlayer after the inserted molecule has decomposed. 2,2''-bis [(dimethylamino)methyl]biferrocene has been synthesised and intercalated into acid exchanged Westone-L. Variable temperature Mossbauer spectroscopy revealed a Debye temperature of 172 +/- 5 K which dropped to 150 +/- 5 K on intercalation. The molecule was shown to occupy 75 % of the total CEC of the clay and most likely resides with the cyclopentadienyl rings perpendicular to the silicate sheet. Thermal decomposition of the biferrocene intercalate indicated the loss of iron containing fragments below 430°C. Variable-temperature XRD indicated a d[001]-spacing of 1.65 nm at room temperature which collapsed to 1.41 nm at 250°C, after which it slowly decreased to 1.29 nm at 400°C. An iron oxide was probably left within the interlayer after the intercalated molecule had decomposed. Contact of the biferrocene with the acid Westone-L for 3 and 48 hours resulted in 2 and 11 % oxidation to biferrocenium respectively. Contact of iodine with a suspension of the intercalated biferrocene resulted in ca. 16 % oxidation to biferrocene. The biferrocenium intercalate exhibited "domain" type valence electron de-trapping above 200 K until by 250 K only a single charge averaged doublet was observed. The molecule N,N-dimethylaminomethylferrocene was successfully intercalated into aluminium pillared Westone-L, occupying 30 % of the total CEC of the original clay. The inserted molecule was found to have a Debye temperature of 113 +/- 5 K as determined by variable temperature Mossbauer spectroscopy. Decomposition of the inserted molecule involved the loss of iron containing fragments below 350°C. When heated in air the inserted molecule gave rise to high spin iron(IH) in a distorted octahedral environment. Heating the sample in nitrogen and hydrogen resulted in a species characteristic of high spin octahedrally co-ordinated iron(II). At the higher temperatures, the sample heated in hydrogen exhibited a further high spin octahedrally co-ordinated iron(K) species, with a less symmetric co-ordination sphere than the first.

Item Type: Thesis (Doctoral)
Additional Information: Thesis (Ph.D.)--Sheffield Hallam University (United Kingdom), 1998.
Research Institute, Centre or Group: Sheffield Hallam Doctoral Theses
Depositing User: EPrints Services
Date Deposited: 10 Apr 2018 17:20
Last Modified: 14 May 2018 08:31
URI: http://shura.shu.ac.uk/id/eprint/19748

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