Metallocenes ferrocene polymers

Ferrocene is a very robust organometallic complex that has been incorporated into an impressive number of molecules with various applications and properties. Therefore, ferrocene-containing polymers have been pursued for many possible applications by different routes. Three metathesis-based approaches toward metallocene-containing polymers (mainly ferrocenes) have been reported so far (i) homo-ROMP or co-ROMP of olefins bearing a metallocenyl substituent, (ii) ROMP of strained an.ya-metallocenes, and (iii) ADMET polymerization of bis(alkenyl)metallocenes, including ADMET copolymerization with a.ty-dienes. 

Since the first example of a metallocene based polymer was reported in 1955 by Arimoto and Haven, just a few years after the discovery of ferrocene, there has been an ever increasing interest in the development of oiganometallic polymers. This... 

Research in metallocene-containing polyamides, polyureas, polyuretiianes, and polyesters continued to be conducted in the 1980s, and since that time, research into these classes of materials has continued to grow7 Homoannular and heteroaimular liquid-crystalline polymetallocenes have been prepared by Zentel and coworkers through condensation reactions. Ferrocene-based liquid-crystalline polymers have also been reported by Senthil and Kannan. The synthesis of ferrocene polymers containing backbone organophosphorus moieties 32 is shown in scheme 9. 

While ferrocene-derived polymers continue to be the best studied of the metallocene-based polymers, there exists a wide variety of other (symmetric) metallocenes. The metallocene portion of the polymer can be bound through the metallocene ring, through adjacent metallocene rings, or through the metal itself. Metallocenes may exist... 

Metallocene-containing polymers are often related to prominent ferrocene and cobaltocene [136-139]. Work in this area has been reviewed recently [140-142]. Therefore, the following serves as an overview. 

Ferrocene has been extensively used as a building block to prepare organo-metallic polymers and heteroatom-bridged poly(metallocenes)(G )-(G ")(Fig 4). 

Third, metallocene units, such as ferrocene or ruthenocene, have been linked to phosphazene cyclic trimers or tetramers and these were polymerized and substituted to give polymers of the type mentioned previously (41). Polyphosphazenes with ferrocenyl groups can be doped with iodine to form weak semiconductors. Polymer chains that bear both ruthenocenyl and ferrocenyl side groups are prospective electrode mediator systems. 

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. 

Ferracyclic carbenes, with alkenes, 6, 133 Ferracyclopentendiones, preparation, 6, 82-83 Ferraoxetene, synthesis, 6, 82 Ferricenium, characteristics, 12, 449 Ferrocene-acetylene polymers, with metallocene units,... 

A number of organometallic polymers containing metallocenes and metallocene analogues has been well-known for some time2. Because of the features of high-temperature stability and radiation resistance of the ferrocene nucleus, ferrocene-containing polymers are of special interest. Basically, these polymers may be divided into two classes the metallocene moiety is either located in a pendant group or in a backbone of the polymer chain. The former polymers have been synthesized by vinyl polymerization of vinyl metallocene monomers such as vinylferrocene. The latter polymers have been prepared by polycondensation of l,l -disubstituted metallocenes or metallocene dihalides with a.w-disubstituted monomers, and fell into two main types, (A) and (B). 

One of the syntheses of the polymers of type (A) and (B) involves the polycondensa-tion of a metallocene-containing Lewis base or Lewis arid71. A number of ferrocene-and cobalticenium-containing Lewis bases have been employed, e.g. ... 

Only recently has the field of metallocenes become of interest to polymer chemists. Ferrocene (I), being the oldest, most readily available, and best characterized of the class, was the logical choice for initial studies. Ferrocene and vinyl ferrocene (II) can be thought of as analogs of benzene and styrene, respectively, undergoing many of the same kinds of reactions. Including polymerization of vinyl ferrocene. Two excellent reviews of the... 

The electropolymerization of metallocene-functionalized pyrrole and thiophene has been utilized for the creation of organometallic polypyrroles and polythiophenes.181 241 242 243 Zotti et al. reported the electrochemical homo- and copolymerization of ferrocene-functionalized pyrrole, 177.242 Polymer 179 was prepared via the copolymerization of monomer 177 with pyrrole (Scheme 2.48). This polymer possessed an electrical conductivity of 1.5 X 10-2 S/cm. 

Metallocene polymers, which contain a metal sandwiched usually between the cyclopentadienyl moieties, are the most investigated M—C-containing polymers ". Ferrocene containing metallocenes are by far the most studied, followed by cobalticen-ium, with some work where the metal is Ni, Rh, Ro or Ru. 

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 . 

A variety of other organic polymers with metallocene-containing side-groups have been synthesized. However, very few of the materials have been as well studied as PVEc. Crystalline organometallic complexes containing ferrocene... 

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