POLYMERIZATION OF ACETYLENES CATALYZED BY RHENIUM CARBONYL HALIDES.

Results of an experimental study are presented which show that the homogeneous catalyst Re(CO)//5X (X equals Cl, Br) promotes the homopolymerization of terminal alkynes at elevated temperatures. Detection and structure characterization of low-molecular-weight products provided evidence of the formation of a metal-acetylide species as the initiator of polymerization, and propagation occurs by a series of insertion reactions of coordinated alkynes into metal-carbon bonds of the growing chain. Evidence of the active forms of the catalyst comes from studies on gas evolution, catalyst derivation, and copolymerization reactions. The final polymers have a linear, polyconjugated macrostructure, and the formation of aromatic species was not detected in these reactions.