Polymerization of silylacetylenes by W and Mo catalysts

Polymerization of HCCSiMe 3 homologues (HCCSiMe 2 R; R = n ‐C 6 H 13 , CH 2 CH 2 Ph, CH 2 Ph, Ph, and t ‐Bu) was studied by use of W and Mo catalysts. W catalysts provided polymers in good yields from all these monomers. Mo catalysts gave mainly a polymer from HCCSiMe 2 – t ‐Bu, but virturally only cyclotrimers from sterically less croweded monomers (R = n ‐C 6 H 13 , CH 2 CH 2 Ph, CH 2 Ph, and Ph). Polymers with flexible R groups ( n ‐C 6 H 13 , CH 2 CH 2 Ph, and CH 2 Ph) were totally soluble, their number‐average molecular weights being 7000–18,000. Polymers with inflexible R groups (Ph and t ‐Bu) were partly insoluble. Every polymer was a yellow rubber or powder, and had the structure, {article}{empty}{document}-- [ CH = C( SiMe₂ R )-- ]ₙ{document} . The results were compared with the polymerization and polymer of HCCSiMe 3 .