Organometallic polymers ferrocenes

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. 

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). 

Organometallic polymers, in contrast to coordination polymers, have metal-to-carbon bonds. They are the topic of this chapter. Three seminal events provided the foundation for the field of organometallic polymers to develop. The landmark discovery of ferrocene by Kealy and Pauson in 1951 marked the first organometallic compound.11 This was quickly followed by the full elucidation of its structure and an understanding of its reactivity by Wilkinson, Rosenblum, Whiting, and Woodward.12,13 This history was celebrated in a 2001 feature article in Chemical and Engineering News 4 Finally, the first polymerization of an organometallic compound was reported by Arimoto and Haven at Dupont Co. in 1955.15,16 Vinylferrocene 1... 

Fig. 27. The first oligomeric unit (123) of an organometallic polymer containing ferrocene- and [2.2]paracyclophane units (reaction paths j and k) [103,105]...

Interest in organometallic maaomolecules has grown exponentially ever since Arimoto and Haven first polymerized vinylferrocene in 1955 [1]. Organometallic polymers are known to possess unique optical, magnetic, and thermal properties which allow for potential applications as chemical sensors, electrocatalysts, modified electrodes, and photo-active molecular devices [2-7]. Organoiron polymers are one of the most prevalent classes of organometallic polymers, with many reports on their synthesis and properties published over the past 50 years [8-11]. Of the many varieties of organoiron species, ferrocene and cationic cyclopentadienyliron complexes are most commonly incorporated into polymers. 

One of the most important methods for obtaining organometallic polymers is poly condensation. In 1961 Knobloch and Rauscher reported the synthesis of polyesters and polyamides with ferrocene groups in their backbones using interfacial polymerization. 

Sidechain ferrocene-based polymers possessing nonlinear optical properties have been described by Wright and coworkers as shown in Scheme The copolymerization of 5 mol% of the ferrocenyl functionalized monomer 28 with methyl methacrylate 29 resulted in an organometallic polymer (30) displaying second-harmonic-generation activity. The Tg and T values of this organometallic polymer were 120 and 225°C, respectively, which are similar to those of poly(methyl methacrylate). 

The landmark discovery of ferrocene by Kealy and Paulson in 1951 marked the beginning of modern organometallic chemistry. The first organometallic addition polymer was polyvinyl-ferrocene synthesized by Arimoto and Haven in 1955. While polyvinylferrocene (structure 11.32) had been synthesized it was about another decade until the work of Pittman, Hayes, and George, and Baldwin and Johnson allowed a launch of ferrocene-containing polymers. 

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