Cobaltacyclopentadiene-containing polymers

B. Conversion of Cobaltacyclopentadiene-Containing Polymers into Polymers Possessing Various Mainchain Structures... 

Accordingly, this chapter deals the synthesis and the reactions of polymers containing reactive organometallics such as cobaltacyclopentadiene and titana-cyclopentadiene units in the mainchain. That is, cobaltacyclopentadiene-containing polymers have been prepared by the metallacyclization process of a low-valent cobalt... 

The synthetic methodology used by Tilley is similar to that used by Nishihara and Endo to prepare polymers witb cobaltacyclopentadiene groups in the back-bone. For example, Scheme 6 shows the reaction of 24 with 25 to produce the cobaltacyclopentadiene-containing polymer (26). Reaction of polymer 26 with an isocyanate (27) resulted in the formation of a 2-pyridone ring (28). 

Cobaltacyclopentadiene polymers undergo thermal rearrangement to the more stable ( /" -cyclobutadiene)cobalt derivatives, and reaction with isocyanates affords new polymers containing 2-pyridone moieties in the polymer backbone (for details, see Chapter 4, Section 4,4.1) [98-100],... 

Ph-C=C-A-C=C-Ph (A = / -phenylene, 4,4 -bipheny-lene, /J-C6H4CH2CH2-P-C6H4) [140]. This reaction gives polymers 68a-c, with = 9600, 5100 and 4200, respectively. These polymers can be used for chemical transformation based on the established chemistry of cobaltacyclopentadiene complexes [154]. Pyrolysis of 68a in THF in a sealed tube at 110°C gives a product with cyclobutadiene complex units, 69 [155] and reaction of isocyanates a product containing 2-pyridone units, 70 [156].-... 

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