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Polymerization of t-Butylacetylene by Group 6 Transition Metal Catalysts: Geometric Structure Control by Reaction Conditions

The geometric structure of poly(t-butylacetylene) could be controlled by the choice of suitable polymerization conditions (solvents and catalysts): t-Butylacetylene was polymerized in high yield by MoCl5 and WCl6 in oxygen- or nitrogen-containing solvents (e.g., anisole, acetophenone, benzonitrile and nitrobenzene). The molecular weights of the polymers formed were as high as 5×104—2×105. According to 13C NMR, polymers prepared in nonpolar solvents like toluene comprised comparable amounts of cis and trans structures. On the other hand, polymers obtained with MoCl5 in oxygen- or nitrogen-containing solvents possessed the cis structure exclusively. The mechanism of geometric structure control was discussed.