Lead halides, coordination polymers

Attempts to perform the cationic polymerization of vinylcyclohexane have been reported. While coordination-type polymerization of vinylcyclohexane monomer gives isotactic PCHE, polymerization under conditions that lead to the formation of carbocationic intermediates leads to polymers with a differentiated backbone structure. Instead of propagating via the vinyl carbons, the cationic polymerization proceeds via hydride shift to a tertiary carbocation, which then propagates to provide the polymer shown in Scheme 23.3 [32]. Conditions for these polymerizations typically involved the use of aluminum halide catalysts in halogenated hydrocarbon solvents at low temperatures [32,38]. For the most part, molecular weights are relatively low. 

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