Cationic organoiron moieties

Polymers 39 containing both neutral and cationic organoiron moieties as well as azo dyes in their backbone were isolated from the condensation polymerization of azo dye-containing organoiron monomers 37 with various N-, S-, and 0-containing... 

Polymers containing both netural and cationic iron moieties have been prepared from organoiron complexes containing ferrocene and azo dyes in the main chain with pendent cationic iron units. The monomers were prepared by first reacting bifunctional azo dyes 34 with the organoiron complex (1) (Scheme 7.11). 

Monomers 49 and 50 were subsequently reacted with 2d, 7, and lOd in the presence of potassium carbonate in DMF, resulting in the formation of polymers 51a-f as shown in Scheme 14. These polymers are unique in that they bear neutral ferrocenyl units in their backbones and cationic cyclopentadienyliron moieties pendent to their backbones. These polymers were isolated as orange solids in yields ranging from 86 to 91%. These organoiron polymers demonstrated good solubility in polar organic solvents such as DMF and DMSO. 

Polymethacrylates and polystyrenes with cationic cyclopentadienyliron moieties coordinated to their sidechains were prepared by radical polymerization of their corresponding organoiron monomers as shown in Scheme 19. Electrochemical analysis showed that the cyclopentadienyliron coordinated monomers (74) and polymers (75) underwent reversible reduction processes. Photolytic demetallation of die cyclopentadienyliron-coordinated polymethacrylates resrrlted in the corresponding organic analogs with M =48,000-68,000. 

Nishihara has reported the complexation of poly(hexyl phenylene) with cyclopentadienyhron, where approximately 1 in every 1.6 aromatic rings was coordinated to the metalhc moiety. Spectroelectrochemical analysis of this organoiron polymer (40) suggested that a network was formed between the aromatic rings of neighboring polymer chains following reduction of the cationic iron centers to the neutral radicals. 

Ring-opening metathesis polymerization (ROMP) of norbornene monomers (91) (Scheme 11) fimctionalized with cyclopentadienyliron cations has been accomplished using transition metal catalysts to yield the corresponding organoiron polymer (92). The resulting polynorbomene has the metallic moieties present in the... 

Two main classes of T -dienyliron complexes are known, namely the cationic tricarbonyliron complexes and neutral cyclopentadienyliron compounds. The cyclopentadienyl (Cp) ligand is relatively inert to a broad variety of reaction conditions. It is often introduced as a ligand to tune the properties of the iron complex, as a chiral auxiliary,or in material science in organoiron pol5miers. However, it is only rarely transformed itself into a more elaborate organic product. For this reason, the chemistry of the cyclopentadienyl ligand will not be discussed in more detail in this chapter. Tricarbonyl( n -dienylium)iron complexes, on the other hand, represent versatile electrophilic building blocks for the attachment of 1,3-butadiene, cyclohexadiene, or aromatic moieties to nucleophilic molecules. 

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