Tungsten salts alkenes

More recently, a Pd(II) salt was shown to catalyze the 1,2-insertion polymerization of a 7-oxanorbornadiene derivative (Fig. 10-16) [50]. The resulting saturated polymer, when heated, gives polyacetylene via a retro-Diels-Alder reaction. (This reaction is reminiscent of the Durham route to polyacetylene discussed below). One advantage of this technique over other routes is that it employs a late transition metal polymerization catalyst. Catalysts using later transition metals tend to be less oxophilic than the d° early transition metal complexes typically used for alkene and alkyne polymerizations [109,110]. Whereas tungsten alkylidene catalysts must be handled under dry anaerobic conditions, the Pd(II)-catalyzed reaction of water-insoluble monomers may be run as an aqueous emulson polymerization. 

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