Ferrocene-containing polymers. A reinvestigation of the polyrecombination of ferrocene

Earlier work by Korshak and other Russian authors on the preparation of polyferrocenylenes by the recombination reaction of ferrocene in the presence of tert-butyl peroxide has been reinvestigated. It has been demonstrated that, under carefully controlled conditions at temperatures near 200°, ferrocene can indeed be polymerized to give soluble polymeric compounds, comparable in molecular weight range and physical properties with Korshak's products. These polymers, however, possess overall elemental compositions distinctly differing from that of polyferrocenylene. Spectroscopic and elemental analyses, corroborated by the isolation not only of biferrocenyl and terferrocenyls, but also of diferrocenylmethane and ferrocenylmethyl tert-butyl ether as by-products, indicate the polymer chains to be composed of small polyferrocenylene segments interlinked by methylene and aliphatic ether groups. These bridging groupings are believed to have arisen through the involvement of methyl and tert-butyl radicals generated by thermal decomposition of the tert-butyl peroxide, with methylferrocene postulated as an additional intermediate. Consistent with the presence of such non-ferrocene constituents, the polymers exhibit poor hydrolytic stability and, in thermogravimetric analysis, show a thermal stability behavior inferior to that expected for a polymeric compound strictly composed of ferrocenylene units.