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Grafted metallo‐carbynes as bifunctional pre‐catalysts for ROMP of cyclo‐octene and cyclic alkane metathesis

Abstract: Metallo‐carbynes grafted on mesoporous fibrous silica are active towards alkane metathesis. We are comparing the activity of well‐defined grafted pre‐catalysts (≡Si−O−)W(≡CCMe3)(i−CH2CMe3)2, (≡Sii−Oi−)W(≡CH)(i−CH3)2 and (≡Sii−Oi−)Mo(≡CCMe3)(i−CH2CMe3)2 for Ring Opening Metathesis Polymerization of cyclo‐octene and metathesis of cyclo‐octane. This comparison is because olefins are assumed to be intermediate products in alkane metathesis. The three pre‐catalysts are active in cyclo‐octane metathesis, and give the higher, and lower cyclic homologues. However, with cyclo‐octene the three catalysts give polyoctenamer by classical ROMP. It is assumed that the metallo‐carbynes react differently towards cyclo‐alkanes and cyclo‐olefins. In one case, with cyclo‐alkanes they give a metallo‐carbene alkyl and in the other case with cyclo‐olefins they give a bis‐carbene.