Olefin-metathesis reactions using vinylideneruthenium(II) complexes as catalyst precursors

Vinylideneruthenium(II) complexes of the type RuCl2(=C=CHR)L-2 (R = Bu', ferrocenyl; L = PPr3' PCy3), which are easily accessible from [RuCl2(p-cymene)](2) and terminal alkynes, have been found to serve as good catalyst precursors for ring-opening metathesis polymerization (ROMP) of cyclic alkenes and ring-closing metathesis (RCM) of alpha,omega-dienes, alpha,omega-enynes, and dienynes. These complexes possess high stability toward air and heat, compared with the metathesis-active alkylidenerutheniums. Molecular weight control of poly(norbornene) in extremely wide range (M-n/10(3) = 500-4) has been achieved by using heteroatom-substituted vinylic compounds such as ethyl vinyl ether and phenyl vinyl sulfide as chain-transfer agents for ROMP. (C) 2000 Elsevier Science S.A. All rights reserved.