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.