| Abstract: | Polymerization of homologues of 1-(trimethylsilyl)-1-propyne CH3C?CSi(CH3)3] was studied. CH3C?CSi(CH3)2(n-C6H13) ( I ) polymerized with 1 : 1 mixtures of TaCl5 and organometallic cocatalysts (e.g., Ph4Sn and Ph3Bi) to produce in good yields a polymer having a weight-average molecular weight (M w) over 1 × 106. CH3C?CSi(CH3)2 Ph ( II ) and CH3C?CSi(C2H5)3 ( III ) formed polymers having M w's of ～ 5 × 105 in moderate yields in the presence of TaCl5-based catalysts. In contrast, none of CH3C?CSi(CH3)2(i-C3H7), CH3C? CSi(CH3)2(t,-C4H9), C2H5C?CSi(CH3)3, and n,-C4H9C?CSi(CH3)3 polymerized, which is attributed to the steric effect of the monomers. Some other 1-silyl-1-propynes also failed to polymerize. The three new polymers formed from ( I )–( III ) had the structure \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} {\rm CCH}_{\rm 3} \hbox{=\hskip-2pt=} {\rm C(SiRR'R''}\rlap{--} ]_n$\end{document} according to IR and 13C-NMR spectra. They were white solids, soluble in low-polarity solvents (e.g., toluene and chloroform) and stable enough in air at room temperature. |
