Ferrocenes condensation polymers

Properties of ferrocene-containing polymers have been improved by inclusion of pyrazole systems in the backbone. The synthesis of (748) was achieved by condensation of bis()3-diketoferrocenes) with aromatic dihydrazines to give polyhydrazones that were later cyclo-dehydrated (B-80MI40408). 

Ferrocene containing condensation polymers have been utilized by us to modify the surfaces of electrodes.Materials of this type that incorporate organo-iron compounds into a polymer matrix, either through chemical bonding or by formation of blends, have the potential of being thermally processed to yield iron oxides. 

One previous synthesis of ferrocene-containing condensation polymers via interfacial methods at room temperature has been reported by Knobloch and Rauscher, who formed low molecular weight polyamides and polyesters by reacting l,l -bis(chloro-formyl)ferrocene with various diamines and diols. Further, Carraher and co-workers have utilized interfacial techniques in the formation of other types of organometallic polymers. 

The advantage of these polymers over poly(vinylferrocenes) or related species with pendent organometallic units is that the condensation polymers have ferrocene units in the main chain where they can exert their maximum influence on polymer thermal stability. The disadvantage of the condensation products is that, except in the last example, the molecular weights are too low to favor fiber or flexible film formation. Nevertheless, this work indicated the potential usefulness of polymers with metallocene units in the main chain. 

Ferrocene has been reported to be very effective as a soot reducing agent in combustion [42 — 44]. Thus, when ferrocene compounds are incorporated in a fire retardant polymer, such as a phenolphthalein-based polymer and poly(phosphate ester)s, they have shown added advantages in that they promote extinction and reduce smoke formation by accelerated char reduction [45, 46]. The synthesis of such ferrocene-containing poly(phosphate ester)s was achieved by interfacial polycondensation using a phase transfer catalyst [47]. Accordingly, l,l -bis(p-hydroxy-phenylamido)ferrocene and l,l -bis(p-hydroxyphenylcarbonyl)ferrocene underwent condensation with various aryl phosphoroic acid dichlorides to yield two series of ferrocene-containing polymers, i.e., poly (amide-phosphate ester)s 38a and poly(ester-phosphate ester)s 38b respectively, as shown in Scheme 10-17. 

A. Condensation Routes to Main Chain Ferrocene-Organosilane Polymers... 

Condensation approaches to ferrocene/organosilane polymers have been extended to the synthesis of low molecular weight materials 11 (jc = 6, R = Me) with M 3500 from the reaction of dilithioferrocene-tmeda with the dichlorohexasilane Cl(SiMe2)6Cl (39). These polymers were shown to possess electrical conductivities in the range of 10" -10 S/cm... 

Other approaches of preparing condensation polymers of ferrocene involve the use of conventional organic functional groups. The resulting polymers are essentially organic polymers. In an example that typifies this approach Rausch and coworkers have prepared a number of ferrocene-based difimctional reagents (Fig. 8.4) [27]. 

A different strategy from the above consists in the incorporation of silylamino groups on ferrocene. Condensation of such difunctional reagents with disilanols leads to the formation of polymers where the ferrocene groups are separated by organosilicon spacers [28] (Fig. 8.7). 

Condensation polymerization of functional ferrocenes generally yields medium- or low-molecular-weight polymers with broad molecular-weight distributions.12 For example, ferrocenylcarbinol, 6.9, has been condensation-polymerized to polymers 6.10 and 6.11 in the presence of boron trifluoride etherate or zinc chloride (reaction (5)).910 Species 6.11... 

In other examples, compounds in which a metal atom is already coordinated in a molecule can be used as a comonomer in an addition polymerization. Two examples involve the ferrocenes discussed in Chapter 6. The vinyl ferrocene molecule is shown in 7.14, and a similar vinyl manganese complex in 7.15.30 An alternative approach involves condensation polymerization. For example, if the R group in the ferrocene unit shown in 7.16 contains a hydroxyl group, it can be copolymerized with a diacid chloride. If it is an acid chloride, it can be copolymerized with a diamine. (This type of polymer is called a heteroannular chain if only one of the rings in the repeat unit is in the backbone, the polymer is called homoannular.)7 Similarly, the titanium complex shown in 7.17 is copolymerized with diacids or diols.30 Numerous other examples involving ferrocenes are discussed in Chapter 6. 

Polypyrazoles of the type 62 have been prepared.65 These polymers are formed from the low-temperature solution condensation of 1,1 -bis(diketo)ferrocenes with aromatic or pseudoaromatic dihydrazines to give polyhydrazones which are transformed thermally to the polypyrazoles. Polybenzimadazole (63) has been prepared68 from l,l -ferrocenedicarboxylic acid and 3,3 -diaminobenzidine. 

Previous attempts to synthesize ferrocene-backbone macromolecules of type 4 (y > 0) in which the ferrocene units are separated via a spacer group have also focused on the use of condensation reactions. Polymers 4 (y > 3) in which the spacer is very long have been successfully prepared (36), but well-characterized materials of substantial molecular weight where the ferrocene units are held in close proximity to one another are extremely rare. Previous work on such polymers and other ferrocene-... 

Condensation routes to polymers with ferrocene groups separated by short hydrocarbon spacers have mainly resulted in the preparation of low molecular weight and poorly defined materials (2). For example, poly(fer-rocenylmethylene), formally 28, has been previously prepared via the... 

Polymer formation can occur through a variety of reactions. Metallocene polyamides, polyethers, polyesters, polyhydrazides and polyurethanes have been synthesized through condensation reactions of 1,1 -difunctional metallocenes (typically ferrocene derivatives) with diacid halides (if the metallocene derivative contains functional electron-pair donor bases) and electron-pair donor bases (as diamines, hydrazines, diisocyanates, diols) if the metallocene derivative contains functional electron-pair acceptor acids . 

J/n < 6,000). Often, no analytical data or structural characterization was provided. Room-temperature interfacial polycondensation methods were also investigated as a convenient alternative to classical polycondensations. Such methods were first reported for the preparation of polyamides and polyesters from the reaction of l,l -ferrocenyldi-carbonyl chloride with several diamines and diols. The synthesis of polyurethanes using this technique was also reported and involved the condensation of l,T-ferrocenedimethanol and l,T-bis(dihydroxyethyl)ferrocene with diisocyanates. Once again, however, these polymers possessed low molecular weights.The early research in these areas has been summarized and critically reviewed and will not be discussed further here. ... 

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