Polymerization of acetylenes catalyzed by arene–group vib tricarbonyls

Abstract

Abstract The polymerization of phenylacetylene and other terminal and internal alkynes has been achieved in homogeneous reactions catalyzed by ArM(CO) 3 , where Ar is an arene; M is Cr, Mo, or W. The polymerization of phenylacetylene proceeds by way of an intermediate which has been isolated and identified as a ladder compound composed of fused cyclobutane rings. The ladder compound, which is stable in the absence of the catalyst, breaks down in the presence of the catalyst to give the final polyconjugated polymer. Available evidence indicates that the conversion of the ladder compound to polyphenylacetylene proceeds by way of a free‐radical mechanism. A mechanism for the electronic conversion of the ladder compound to the final polymer is proposed, as is a method of chain propagation.