Reactivity of Secondary Metal−Alkyls in Catalytic Propene Polymerization:  How Dormant Are “Dormant Chains”?

In this communication, we report on the direct measurement of dormant chain concentration and of the relative reactivity of authentic primary and secondary Zr−polymeryls toward propene, ethene, and H₂ under practical conditions for a new highly regio- and stereoselective postmetallocene polymerization catalyst with controlled kinetic behavior. The results, in particular, confirm the poor reactivity toward propene of secondary M−polymeryls and the possible accumulation of dormant chains in propene homopolymerization.