Redox-Active Polyferrocenylsilane Gels

The metal-metal interactions in the polymer network were investigated by controlled potential electrolysis with the aid of an optically transparent thin-layer electrochemistry (OTTLE) cell. In the visible/near-IR spectrum of the fully reduced deep-red/orange gel the lowest-energy visible band is assigned to a d-d transition. Upon oxidation, two new absorption peaks emerge one at 640 nm is due to a li-gand-to-metal charge-transfer (LMCT) of the ferrocenium moiety, whereas the 

By means of an alternative sol-gel hydrolytic approach, poly(ferrocenylalkoxy-silane)s have also been incorporated into gels and oxide matrices. For example, poly(ferrocenylalkoxysilane)s 3.25 (OR=OMe, 0 Pr, or OCH2Ph) (see Eq. 3.11, p. 84) were hydrolyzed in water using fluoride catalysts to afford orange, insoluble solids, which retained the electrochemical properties of the ferrocene units [121]. 

5 Thermal Stability and Conversion to Nanostructured Magnetic Ceramics 

The use of highly crosslinked polyferrocenylsilane networks 3.48 x=y=0) leads to much improved ceramic yields (ca. 90%) and the pyrolytic formation of shaped, magnetic ceramics is efficient. The crosslinked network can be formed by heating the [l]silaferrocenophane, 3.47, in a mold (for 7 h at 150°C and then for 16 h at 180°C). The shape of the resulting crosslinked network 3.48 (x=y=0) resembles the mold used, such as a pentagon (Fig. 3.11). 

Pyrolysis of molded samples of 3.48 (x=y=0) above 500 °C leads to ceramics with a very small associated weight loss and contraction ( 10%), which allows retention of the overall shape (Fig. 3.11a) [124, 125]. Furthermore, at 600°C, the for- 

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